5/5/26
Numerous factors—from changes in air temperature to the tug of nearby storms—can affect a tornado’s development. Unlike hurricanes, which can be spotted days off shore, tornadoes develop over the course of hours or minutes, which makes taking on-the-ground measurements even more challenging.
A. NO CHANGE
B. affect a tornadoes development.
C. effect a tornado’s development.
D. effect a tornadoes development.
Affect is a verb, whereas effect is a noun. Because a verb must follow can, affect is the correct version, eliminating (C) and (D). (B) can be eliminated as well because tornado must be possessive rather than plural: tornado’s development = development of a tornado. Tornodoes is the plural form (note the lack of an apostrophe). The original version provides the correct form of both words, making (A) correct.
5/4/26
The cognitive scientist Rafael Núñez of the University of California at San Diego doesn’t buy the conventional wisdom that people have a naturally innate capacity for understanding numbers. Rather, he thinks that “number sense” is a product of culture, like writing and architecture.
A. NO CHANGE
B. a natural and innate
C. a natural, innate
D. an innate
Natural and innate (inborn) have the same basic meaning, so it is redundant to use both words. Only one is sufficient, making (D) correct.
5/3/26
The emperors of the Tang Dynasty (618 – 907 AD) are believed to have been the first to eat a frozen, milky confection. This early version of ice cream was made with cow, goat, or buffalo milk that was heated with flour. Camphor, an aromatic substance harvested from evergreen trees, was added to enhance the texture and flavor. Subsequently, the mixture was placed into metal tubes and lowered into an icy pool until frozen.
A. NO CHANGE
B. Nevertheless,
C. Thus,
D. Despite this,
The easiest way to answer this question is to recognize that the passage is describing the steps used to make an early version of ice cream. Logically, the mixture must have been frozen after all the ingredients were added — in other words, the mixture was heated and had camphor added to it, and afterward it was placed into metal tubes and lowered into an icy pool. Subsequently is a transition word meaning “then” or “after,” so (A) is correct. There is no contradiction between the sentence begun by the transition and the previous sentence, so (B) and (D) do not fit. (C) does not make sense either because the freezing of the mixture did not directly result from the addition of all the ingredients; this step merely took place at a later time.
5/2/26
Despite the economic promises touted by supporters of the Golden Gate Bridge, the project met fierce resistance from an array of business and civic leaders. Not only would the bridge impede the shipping industry and mar the bay’s natural beauty, they argued, it wouldn’t survive a trembler like the San Francisco Earthquake that crippled the city in 1906.
A. NO CHANGE
B. it also won’t survive
C. and it also wouldn’t survive
D. but it also wouldn’t survive
To answer this question, you must consider the beginning of the sentence — the underlined portion does not give you enough information to determine the correct option. The first words of the sentence are Not only, which must be paired with but (also). (D) is the only answer that contains this construction, so it is the only possible answer.
5/1/26
Before I started working on real-world robots, I wrote about their fictional and historical ancestors. That wasn’t too different from what I do now. In factories, labs, and of course science fiction, robots continue to fuel our imaginations about artificial humans and smart machines.
Which of the following would NOT be an acceptable alternative to the underlined word?
A. nourish
B. fire
C. supply
D. stimulate
Nourish, fire, and stimulate are all idiomatic ways to indicate that something activates or encourages (i.e., fuels) people’s imaginations. Only supply cannot have this connotation. In addition, this word does not fit grammatically: x can supply y with something, but something cannot supply x about y. Because the question asks which word is NOT an acceptable alternative to fuel, (C) is correct.
4/30/26
A beetle’s wings are rarely visible. Hidden behind armored shields on the creature’s back and unfolding in whirring sheets, whisking their clumsy owners away from danger.
A. NO CHANGE
B. back, they unfold
C. back to unfold
D. back and unfold
The original version of the underlined portion creates a fragment because the statement does not contain a main (independent) clause: neither Hidden behind shields on the creature’s back, nor unfolding in whirring sheets, whisking their clumsy owners away from danger can stand on its own as a sentence. That eliminates (A). (C) and (D) are incorrect for a similar reason: each of these answers creates a dependent clause that by definition cannot stand on its own as a sentence. (B) is correct because the words they unfold act as a subject and verb that create an independent clause (they unfold in whirring sheets) and turn the statement into a complete sentence.
4/29/26
In the first half of the twentieth century, tornadoes were said so unpredictable that in order to prevent mass hysteria, the word “tornado” was forbidden from weather forecasts. Progress on the forecasting front moved slowly until the 1970s, when the first Doppler radar allowed scientists to track a storm’s development and spot the signs of a developing twister.
A. NO CHANGE
B. considered
C. viewed
D. described
(A) is incorrect because something is said to be x, but to be does not appear. (C) and (D) are incorrect for a similar reason: described and viewed must be followed by as, but this word is also missing. Only (B) is an acceptable option: although considered can be followed by to be, those words are not required. It is correct to say that something is considered x.
4/28/26
The correlation between bad moods and negative judgments allows people to make informed guesses about how others are feeling by observing their actions and choices.
A. NO CHANGE
B. judgments allow
C. judgments have allowed
D. judgments, which allow
Don’t get fooled by the plural noun judgments, which appears immediately before the verb (allows). In reality, that noun belongs to the prepositional phrase between bad moods and negative judgments, which is placed between the subject (The correlation) and the verb. Correlation is singular, and so a singular (-s) verb is required. That eliminates (B) and (C). (D) can be eliminated as well because this answer creates a fragment: although the plural verb allow agrees with judgments, it also “belongs” to which rather than to the subject of the sentence, The correlation. As a result, the sentence is missing a main verb. (A) correctly supplies a singular main verb (allows) that corresponds to the subject of the sentence.
4/27/26
The original Shinkansen, or bullet train, connects the largest Japanese cities of Tokyo and Osaka, is the world’s busiest high-speed rail line. Carrying 151 million passengers per year, it has transported more travelers than any other high-speed line in the world.
A. NO CHANGE
B. train connects
C. train connects:
D. train, which connects
To answer this question, you must consider the sentence as a whole; the underlined section alone does not give you enough information to determine the correct option. When considered independently, the underlined portion makes sense; however, the construction Osaka, is later in the sentence signals the end of a non-essential clause. In fact, the sentence contains two non-essential clauses placed back to back: or bullet train and (which) connects the largest cities of Tokyo and Osaka. To simplify the sentence and reveal the error, cross out the first non-essential clause: The original Shinkansen…connects the largest Japanese cities of Tokyo and Osaka, is the world’s busiest high-speed rail line. Clearly, that does not work grammatically. Because the end of the sentence cannot be changed, the beginning must be altered to include the start of a non-essential clause. This type of clause cannot begin with a verb; instead, it must begin with a relative pronoun (which). Now, when the first non-essential clause is crossed out, the sentence makes grammatical sense: The original Shinkansen…which connects the largest Japanese cities of Tokyo and Osaka, is the world’s busiest high-speed rail line. That makes (D) correct.
4/26/26
In the mid-nineteenth century, the Oregon Trail was the principle pathway for immigrants seeking land and opportunity on the American frontier. From its main departure points in Missouri, the grueling overland route stretched 2,000 miles over the Great Plains and the Continental Divide, finally ending in the fertile Willamette Valley or the gold fields of California.
A. NO CHANGE
B. principal pathway for
C. principle pathway to
D. principal pathway to
Based on the context, the underlined portion must be referring to the main pathway, i.e., the principal pathway. A principle is a fundamental rule or doctrine. That eliminates (A) and (C). Logically, the Oregon Trail must have been a pathway for immigrants rather than to (toward) them. That eliminates (D) and makes (B) the answer.
4/25/26
A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky, this creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals—the six arms of the snowflake.
A. NO CHANGE
B. sky and create
C. sky, creating
D. sky; creating
(A) creates a comma splice: two complete sentences separated by only a comma (tip-off: comma + this). When plugged in, (B) creates a coherent sentence but a subject-verb disagreement: the subject of the verb is an extremely cold water droplet, singular, whereas create is plural. Creates (parallel to freezes) must be used instead. (D) is incorrect because a semicolon can only be placed between two complete sentences, and creating an ice crystal is not a sentence. (Note that as a general rule, an –ing word should not follow a semicolon.) An –ing word (creating) can, however, be placed after a comma to join an independent and a dependent clause. That makes (C) correct.
4/24/26
Not so long ago, astronomers didn’t know if there were planets outside our solar system or, if there were, whether it could ever be found. But starting with the 1995 discovery of a planet circling the sun-like star 51 Pegasi, there has been a revolution.
A. NO CHANGE
B. this
C. they
D. DELETE the underlined word.
The only noun in the sentence to which the underlined pronoun could refer is planets, plural, so the correct answer must be plural as well. It and this are both singular, so (A) and (B) can be eliminated. (D) does not fit either because the sentence no longer makes grammatical sense when the underlined word is eliminated — a pronoun is needed to refer back to planets. They is plural and agrees with planets, making (C) correct.
4/23/26
In recent years, robotics has found its way into our everyday lives, changing them in fundamental ways. Designers have a central role to play in this process, which they shape the interfaces between humans and machines.
A. NO CHANGE
B. process:
C. process,
D. process that
(A) is incorrect because the word which is unnecessary and creates a nonsense construction. Because which is placed immediately after process, it appears to refer back to process; however, the information that follows (they shape the interfaces between humans and machines) refers to designers. (D) creates the exact same error; it merely replaces which with that. (C) is incorrect because it places a comma before they, creating a comma splice: two complete sentences separated by only a comma. (B) correctly uses a colon to separate two complete sentences and signal that the second sentence explains the first — that is, the second sentence describes the central role in robotics played by designers.
4/22/26
Researchers at the University of Maryland have developed a super-lightweight insulating material that, they claim, could prove to be a superior alternative to styrofoam. The material, made from tiny wood fibers, is called nanowood.
A. NO CHANGE
B. material, that they
C. material that they
D. material and they
Although in most circumstances, no comma should be placed either before or after that, this question is the exception. The key to understanding the logic of the sentence is to recognize that the words they claim, which appear after that, can function as a non-essential clause and must therefore be surrounded by commas. When the clause is removed, the sentence still makes sense: Researchers at the University of Maryland have developed a super-lightweight insulating material that could prove to be a superior alternative to styrofoam. That makes (A) the answer.
(B) is incorrect because it does not make sense to place the comma before that. If the phrase that they claim is removed from the sentence, the result is nonsense: Researchers at the University of Maryland have developed a super-lightweight insulating material could prove to be a superior alternative to styrofoam. (C) is incorrect because if the comma is removed from the underlined portion, the comma after claim no longer marks the end of a non-essential clause and is thus unnecessary.
(D) is incorrect because that rather than and must be used to refer back to insulating materials. Otherwise, the sentence does not make sense: Researchers at the University of Maryland have developed a super-lightweight insulating material and could prove to be a superior alternative to styrofoam. This construction literally indicates that the researchers could be a superior alternative to styrofoam, a meaning that is clearly ridiculous.
4/21/26
Hummingbirds have long intrigued scientists. Their wings can beat 80 times a second, and their hearts can beat more than 1,000 times a minute. They consume nothing but nectar—a sugar- and nutrient-rich liquid produced by plants—they are capable of packing on 40 percent of their body weight in fat for migration.
A. NO CHANGE
B. Because they
C. Although they
D. Since they
Be careful not to focus only on the beginning of the sentence; the information you need to answer the question is elsewhere. Start by eliminating the non-essential information between the dashes to simplify the sentence: They consume nothing but nectar they are capable of packing on 40 percent of their body weight in fat for migration. What remains is clearly a run-on. The first clause must be altered so that it becomes dependent, which means that a transition is required at the beginning of the sentence.
Next, consider what the two statements are saying: 1) Hummingbirds consume only nectar; 2) they can gain up to 40% of their body weight. Because and since are synonyms, so by default, neither (B) nor (D) can be correct. That leaves (C): although correctly conveys the contrast between the single type of food consumed by hummingbirds and the enormous amount of weight they are able to gain.
4/20/26
The Megalodon, a prehistoric ancestor of the modern shark, had a bite force of 12 to 20 tons, somewhere between six and ten times stronger than a modern Great White.
A. NO CHANGE
B. then a modern Great White.
C. than that of a modern Great White.
D. than those of a modern Great White.
(A) incorrectly compares the Megalodon’s bite force (thing) to a modern Great White (animal). Because the first side of the comparison cannot be changed, the second side must be changed so that the bite force of the Megalodon is compared to the bite force of the Great White. (B) contains the same error as (A) and also wrongly uses then instead of than to form the comparison. (D) is incorrect as well because it replaces the singular bite force with the plural pronoun those. (C) correctly uses the singular pronoun that to replace the singular noun bite force. (That of = the bite force of.)
4/19/26
Steve Desch, an astrophysicist at the University of Arizona, can see the future of exoplanet research, and it’s not pretty. Imagine, he says, that astronomers use NASA’s upcoming James Webb Space Telescope to scour the atmosphere of an Earth-mass world for signs of life. They might chase hints of atmospheric oxygen for years before realizing they were false positives produced by geological activity instead of living things.
As it is used in the passage, “scour” most nearly means
A. cleanse
B. consume
C. search
D. burnish
Consider the context: the passage is talking about astronomers who are using a telescope to look carefully for, i.e., search, the atmosphere of a planet for indications of life. Even if you don’t know what scour means, that information is most directly consistent with (B). Cleanse, the literal meaning of scour, consume (eat or use up) and burnish (polish) all do not make sense.
4/18/26
With the car windows down on the first warm day of spring, the urge is unshakable. You extend your arm into the wind, tracing the city skyline in a natural motion somewhere between swimming and waving. As you move your hand, altering the flow of the air. The redirected air in turn exerts a force on your hand.
A. NO CHANGE
B. hand and alter
C. hand, you alter
D. hand to alter
The original version of the underlined portion creates a fragment because the statement does not contain a main (independent) clause: neither As you move your hand, nor altering the flow of air can stand on its own as a sentence. That eliminates (A). (B) and (D) are incorrect for a similar reason: both of these answers create a single clause that begins with as (a subordinating conjunction) and thus cannot stand on their own as sentences. (C) is correct because the words you alter act as a subject and verb that turn the second clause — the information after the comma — into a complete sentence (you alter the flow of air).
4/17/26
Although the concept of sleep-learning, also referred to as hypnopaedia, has been discredited, neuroscientists are now discovering ways to use stimuli such as sound cues during sleep to strengthen peoples’ memories.
A. NO CHANGE
B. peoples memories’.
C. people’s memories.
D. people’s memory’s.
When a question tests two consecutive nouns with apostrophes, the standard pattern is that the first noun is possessive (apostrophe) and the second is plural (no apostrophe). That is the case here: the underlined portion refers to memories belonging to people, so the first noun is possessive. (B) can be eliminated because peoples is plural rather than possessive, so the question becomes whether the apostrophe should be placed before or after -s. For regular nouns, the plural possessive is formed by adding –s + apostrophe, but people, the plural of person, is irregular. When a plural noun is irregular, the plural possessive is formed by adding apostrophe + -s, so (A) can be eliminated. (D) is incorrect as well because memory’s is the singular possessive form. (C) correctly forms the possessive of the first noun by adding apostrophe + -s and the plural of the second by adding -ies. People’s memories = memories of people.
4/16/26
Once upon a time, it seems that Mars had oceans. However, the exact appearance of these bodies of surface water is a matter of intense debate. Most evidence points towards the deep past, some 4 billion years ago, as the age where Mars could have held marine environments. Since then, the red planet has most likely been cold and arid, with only the occasional shift of climate conditions.
A. NO CHANGE
B. in which
C. which
D. in that
Where can only be used to refer to places, not times/time period, so (A) can be eliminated. (C) is incorrect because which alone should not be used to refer to a time period either. (D) is incorrect because in that is a synonym for because, a meaning that does not make sense in this context. The only two options are when and in which. Because when does not appear as a choice, in which must be used. That makes (B) correct.
4/15/26
Baseball has a long and rich history in Japanese-American diplomacy. After the sport was introduced to Japan in the 1870s by the American educator Horace Wilson, it became an important part of Japanese popular culture. Over time, baseball has served as a unifier, bringing together the people of two nations with very different histories and cultures.
A. NO CHANGE
B. educator, Horace Wilson
C. educator, Horace Wilson,
D. educator Horace Wilson
When a name appears in the middle of a sentence, as is the case here, it is always incorrect to place a comma only before the name. As a result, (B) can be eliminated automatically. Placing a comma both before and after a name indicates that the name is being used non-essentially and can be crossed out of the sentence without disturbing its basic structure or meaning. To check (C), cross out Horace Wilson and read the sentence without those words: After the sport was introduced to Japan in the 1870s by the American educator… it became an important part of Japanese popular culture. No, it does not make sense to refer to the American educator without providing his name. Although the sentence is acceptable grammatically, it does not work from a meaning standpoint. Now, the question is whether a comma is needed after the name. In this case, the answer is yes: the sentence begins with a dependent clause (After the sport was introduced to Japan in the 1870s by the American educator Horace Wilson) that is then followed by an independent clause (it became an important part of Japanese popular culture). When an independent clause follows a dependent clause this way, a comma must be used to separate them. That makes the answer (A).
4/14/26
One of the most renowned architects of the twentieth century, Frank Lloyd Wright was the pioneer of the Prairie School movement and he developed the Usonian home, his unique vision for urban planning in the United States.
A. NO CHANGE
B. and developing
C. the developer of
D. had developed
The sentence indicates that Wright was two things: the pioneer of the Prairie School movement of architecture and __________. To keep the sentence parallel, the two sides must match. The non-underlined portion of the sentence contains a noun (pioneer), so the underlined portion of the sentence must contain a noun as well (developer). (C) is the only answer to include this construction, so it is correct. Note that although it is technically grammatically acceptable, if not parallel, (A) does not work because the information that follows and is a complete sentence, and so a comma is required before that word.
4/13/26
In terms of intelligence, the octopus stands far above most other animals. During one really cool study, researchers tested whether this creature is able to distinguish between different people. Two individuals interacted with an octopus, with one acting extremely friendly and another seeming cold and standoffish. Later, when the two people entered the octopus’s living area, the octopus ignored the impersonal one in favor of the friendlier guest.
A. NO CHANGE
B. awesome
C. intriguing
D. totally neat
This question is testing register, or formal vs. informal language. Really cool, awesome, and totally neat are all overly casual when compared to the rest of the passage. Only intriguing is consistent with its moderately serious tone. That makes (C) the answer.
4/12/26
In the early days of mariachi music, players dressed informally. With increased employment opportunities and more formal presentations, however, uniforms became common. When mariachis first acquired the purchasing power to dress their groups in uniforms, the apparel they had chose most often was the charro suit, which consisted of fitted trousers, a short jacket, and an embroidered belt.
A. NO CHANGE
B. have chosen
C. chose
D. choose
All of the non-underlined verbs in the passage are in the simple past tense (became, acquired, was, consisted), so the underlined verb must be in this tense as well. (A) is not only in the past perfect (had + past participle), but it also incorrectly forms this tense: the simple past chose rather than the past participle chosen appears after had. In (B), the present perfect (has/have + past participle) is correctly constructed, but this tense is not consistent with the rest of the verbs in the passage. (D) is incorrect because choose is the present tense, which again does not fit. (C) correctly provides the simple past form, chose.
4/11/26
You can probably recall a situation, in sports or otherwise, in which you felt like you had momentum on your side: your body was in sync, your mind was focused, and you had a high level of confidence. In these moments of flow, success feels inevitable, and effortless.
A. NO CHANGE
B. you had a high confidence level.
C. your high confidence level.
D. your level of confidence was high.
The underlined portion is the third item in a list, and so it must be presented in the same format as the first two items. Both of those items begin with your, so the third item must begin this way as well. That eliminates (A) and (B). (C) is incorrect as well because each of the two previous items contains the pattern your noun + verb, and this answer does not contain a verb. (D) correctly begins the third item with your and includes a verb (was), maintaining the pattern used in the first two items.
4/10/26
Despite decades of research, the sun remains an enigma. Every 11 years or so its activity spikes, creating flares and coronal mass ejections—the plasma-spewing eruptions that shower Earth with charged particles and beautiful auroral displays. Then, however, the so-called solar maximum fades toward solar minimum, and the sun’s surface grows eerie quiet.
A. NO CHANGE
B. eerily quiet.
C. eerie quietly.
D. eerily quietly.
Logically, the suns’s surface must grow (i.e., become) quiet, not quietly, so the second underlined word must be an adjective. That eliminates (C) and (D). The adjective must in turn be modified by an adverb. (How quiet does the sun’s surface become? Eerily quiet). Note that because the adjective eerie already ends in an –ee sound, –ily must be added to form the adverb. (B) is thus correct.
4/9/26
According to research, people are generally biased toward believing that information is true. (After all, most things that we read or hear are true.) In fact, there’s some evidence that we initially process all statements as true and that cognitive effort is required to mentally mark some of them as false.
In the last sentence, the word “mark” most nearly means
A. distort
B. label
C. transmit
D. inscribe
The structure of the sentence provides a subtle but important clue to the meaning of the underlined word. The construction we initially process all statements as true and that cognitive effort is required to mentally mark some of them as false indicates that the word in question must be generally consistent with the idea of processing or perceiving. The only option that makes sense in that context is label: the sentence is saying that the brain requires extra information to assign things to the “false” category, i.e., to label them as such. Transmit (send) and inscribe (engrave) do not fit at all, but be careful with distort: something that is false does indeed provide a distorted picture, but the underlined word itself does not actually have this meaning.
4/8/26
It has taken a while for scientists to piece together the riddle of just when and where cats first became domesticated. In many cases, this type of question can be easily answered by the archaeological record, but in this instance the matter is complicated by the fact that wild cats and domesticated cats have remarkably similar skeletons.
All of the following placements for the underlined word would be acceptable EXCEPT
A. where it is now.
B. after the word can.
C. after the word answered.
D. after the word the.
Easily is an adverb and can only modify a verb. Because modifiers must be placed next to the words they modify, the three acceptable answers must place easily next to verbs. In (A), be is a verb; in (B), can is a verb; and in (C), answered is a verb. Only (D) does not place easily either before or after a verb (the, archaeological). Because the question asks you to identify which placement would NOT be acceptable, (D) is correct.
4/7/26
Knowing that an employee demonstrates high levels of conscientiousness won’t tell you whether his or her work will be careful or sloppy if you inspect it at a particular moment. But if a large company hires hundreds of employees which are all conscientious, this strategy will likely pay off with a small but consistent average increase in careful work.
A. NO CHANGE
B. who
C. whom
D. DELETE the underlined word.
The underlined pronoun refers to employees, i.e., people. Which should be used to refer to things only, so (A) can be eliminated. (C) is incorrect because whom would be placed right before the verb are, and as a rule, whom should not come before a verb. (D) is incorrect because deleting the underlined word would create a nonsense construction (But if a large company hires hundreds of employees are all conscientious…) — a pronoun is needed to refer back to employees. (B) correctly uses who to refer to people. Unlike whom, this pronoun can be placed before a verb.
4/6/26
Growing hardy and plentiful on short, stout bushes, the prairie cherry’s ornamental blooms and glossy leaves produce a deep-red fruit that is less sweet than the traditional cherry, and can be eaten straight from the tree.
A. NO CHANGE
B. cherry, and can be eaten straight,
C. cherry and can be eaten straight
D. cherry and can be eaten straight,
Comma + and = period, but a period cannot be plugged in without creating nonsense: Growing hardy and plentiful on short, stout bushes, the prairie cherry’s ornamental blooms and glossy leaves produce a deep-red fruit that is less sweet than the traditional cherry. Can be eaten straight from the tree. As a result, the comma is unnecessary, and (A) and (B) can be eliminated. (D) is incorrect as well because the comma after straight incorrectly places a comma before a preposition (from). (C) is correct because no punctuation is needed in the underlined section.
4/5/26
During the early days of space travel, astronauts squeezed most of their meals out of tubes. A sugary, orange-flavored drink, sold commercially as Tang, was considered a tasty treat. Food was fuel, and little more. Meals are stored in locker trays held by a net so they won’t float away. In fact astronauts can dine on a variety of freeze-dried meals using regular forks and spoons. And, for a few years, crews in the International Space Station (ISS) have been able to savor a taste of food that’s actually fresh.
Which of the following provides the best transition between the previous sentence and the sentence that follows?
A. NO CHANGE.
B. Salt and pepper are available, but only in liquid form.
C. Today, eating in space has become much less of a chore.
D. Being in space can put a damper on an astronaut’s appetite.
Although the question asks about the underlined portion in terms of the previous and following sentences, you may find it helpful to take more information into account. The beginning of the passage focuses on the fact that eating in space had little resemblance to that act on Earth and involved unappealing food. The latter part of the passage emphasizes that more recently, astronauts’ food has been considerably improved. The underlined portion must therefore set up the contrast between those two ideas and introduce the fact that eating in space is more pleasant than it used to be. In other words, it “has become much less of a chore.” That makes the answer (C). All the other options are off-topic.
4/4/26
Fraudulent images have been around for as long as photography itself, but Photoshop ushered image doctoring into the digital age. Now, artificial intelligence is poised to take photographic fakery to a new level of sophistication thanks to artificial neural networks who’s algorithms can analyze millions of pictures of real people and places and use them to create convincing fictional ones.
A. NO CHANGE
B. who’s algorithms’
C. whose algorithm’s
D. whose algorithms
Who’s = who is, and you would not say …thanks to artificial neural networks who is algorithms can analyze millions of pictures. Rather, the possessive whose must be used. Whose algorithms = the algorithms of artificial neural networks. That eliminates (A) and (B). (C) is incorrect because algorithm’s is possessive, and a possessive noun can only be placed before another noun. The word following algorithms is can, which is a verb, and so no apostrophe should be used. The plural algorithms is thus correct, making (D) the answer.
4/3/26
The human eye may seem capable of taking in a lot of information, but in reality it can focus on only a thumbnail-sized area of vision—the brain fills in the rest. Furthermore, peripheral vision provides less details than central vision does, conveying images at a much lower resolution.
A. NO CHANGE
B. less details then
C. fewer details than
D. fewer details as
Less can only be used to modify singular, non-countable nouns. It would be acceptable to say less detail because detail is singular and cannot be counted, but details is plural and can be counted. Fewer must be used to modify plural nouns, making (C) and (D) the only possible options. In addition, the comparative (-er) form of an adjective must be paired with than, not as, eliminating (D) and making (C) correct.
4/2/26
When trying to learn new material, you might assume that the more work you put in, the better you will perform. Yet taking the occasional down time – to do literally nothing – may be exactly what you need. Dimming the lights, sitting back, and enjoying a few moments of quality contemplation will help one retain the information much more effectively.
A. NO CHANGE
B. us
C. you
D. them
To answer this question, it is necessary to consider the underlined pronoun in the context of the passage as a whole; the sentence in which that word appears does not provide enough information to answer the question. If you look back at the first two sentences, you can notice that they are addressed to you (you might assume, the more work you put in, may be exactly what you need). To keep the passage consistent, you must be used in the last sentence as well, making the answer (C).
4/1/26
Kagome baskets are characterized by a symmetrical pattern of interlaced triangles. A pattern that has preoccupied physicists for decades.
A. NO CHANGE
B. triangles, it is a pattern
C. triangles—a pattern
D. triangles; a pattern
The statement A pattern that has preoccupied physicists for decades is not a complete sentence because it is missing a main verb that corresponds to the subject. The verb has preoccupied “belongs” to the word that rather than to the subject, A pattern. Because it is not a sentence, it cannot follow a period or semicolon, eliminating both (A) and (D). (B) is incorrect because it contains a comma splice — two complete sentences separated by a comma (tip-off: comma + it). (C) correctly uses a single dash to create a single sentence broken into two parts and create a brief dramatic pause between those parts. Note that while a dash used this way must be preceded by a complete sentence, it can be followed by a fragment.
3/31/26
Research suggests that it is possible to cultivate insight by adjusting external conditions. For example, studies show that open surroundings, including high ceilings and tall windows, can broaden one’s perspective. Low ceilings, narrow corridors, and windowless offices have the opposite effect.
Which of the following would be the LEAST acceptable alternative to the underlined word?
A. enlarge
B. raise
C. expand
D. widen
Enlarge, expand, and widen can all be used as synonyms for broaden in order to imply that a person’s perspective is becoming larger or more complete. Only raise cannot have this connotation. This word can only refer to the act of lifting something higher. (B) is correct because the question asks you to identify the LEAST acceptable alternative to broaden.
3/30/26
Robert Wright, the founder of the website Mindful Resistance, claims that meditation, if widely practiced, can help people overcome aggression and other harmful behaviors. Not only does meditation make us happier, Wright says but it also makes us kinder, less selfish, and more considerate of others.
A. NO CHANGE
B. Wright says; but it
C. Wright says, but
D. Wright says, it
The key to answering this question is to recognize that the comma before Wright sets off a non-essential clause that can be eliminated from the sentence without affecting its basic structure: Not only does meditation make us happier…but it also makes us kinder, less selfish, and more considerate of others. A comma cannot be placed only before the non-essential information, as in (A), nor can the end of the non-essential clause be marked by a semicolon, as in (B). (D) supplies the second comma but omits the word but, which must be paired with not only. (C) correctly uses a comma to mark the end of the non-essential clause and includes but.
3/29/26
The Transiting Exoplanet Survey Satellite, or TESS, is the latest effort to try to answer questions that dominate astronomy for the last several decades: Are we alone? Are there other Earths? Evidence of even a single microbe anywhere else in the galaxy would fundamentally change science.
A. NO CHANGE
B. are dominating
C. have dominated
D. dominated
The phrase for the last several decades is a tip-off that the present perfect (has/have + verb) is required: it indicates that the underlined verb describes an action that began in the past and that is continuing into the present. In other words, the questions listed began dominating astronomy several decades ago and are still dominating it today. Only (C) contains the correct construction. (A) and (B) both contain versions of the present: although dominate is the simple present and are dominating is the present progressive, which emphasizes that an action is in the process of occurring, these options are grammatically equivalent. (D) is incorrect because dominated can only refer to an action that began and ended in the past.
3/28/26
For a robot to help scientists truly understand marine life, it must engage with underwater environments without disturbing them. An agile robotic fish created by Massachusetts Institute of Technology researchers does just that. Indeed, it has been observed interacting peacefully with aquatic life along coral reefs in the Pacific Ocean at depths of up to 18 meters.
A. NO CHANGE
B. However,
C. On the other hand,
D. Therefore,
Start by eliminating (B) and (C): however and on the other hand are synonyms, so neither option can be correct — a question can have only one right answer, so if two answers have the same meaning, both must be wrong by default. Now, consider the specific relationship between the last sentence and the information before it. The first two sentences of the passage indicate that MIT researchers have produced a robotic fish that is helpful to researchers because it can engage with underwater environments without disturbing them. The final sentence provides an example of a situation in which the robotic fish was placed underwater without disturbing the environment. That sentence does not describe a result of the previous sentence — it merely illustrates the scenario that sentence describes. As a result, (D) can be eliminated. (A) is correct because Indeed is used to emphasize a preceding statement, and the fact that the robotic fish interact[ed] peacefully with its environment emphasizes the idea that it can engage with underwater environments without disturbing them.
3/27/26
Whereas the tips of most icebergs are covered in densely packed snow or have been weathered by the elements a few rare ones are free of debris and expose glassy, aqua-green ice with water flowing through it.
A. NO CHANGE
B. elements, a few
C. elements; a few
D. elements, and a few
This sentence contains two clauses: a dependent clause (Whereas the tips of most icebergs are covered in densely packed snow or have been weathered by the elements) and an independent clause (a few rare ones are free of debris and expose glassy, aqua-green ice with water flowing through it). When a dependent clause comes before an independent clause, as it does here, a comma must be used to separate the clauses–it is not an option to omit the punctuation, as (A) does. A semicolon cannot be used either: this type of punctuation can only separate two complete sentences, eliminating (C). Comma + and is grammatically identical to a semicolon, so (D) can be eliminated as well. Only (B) correctly provides a comma, making it the answer.
3/26/26
The seeds of the Theobroma cacao tree have, over hundreds of years, been linked to therapies for more than 100 diseases and conditions. Its status as a cure-all dates back over 2,000 years.
A. NO CHANGE
B. It’s
C. Their
D. They’re
The previous sentence indicates that the seeds (plural) of the Theobroma cacao tree have been linked to a wide range of cures, so the underlined pronoun at the start of the following sentence must refer back to seeds and be plural as well. That eliminates (A) and (B). (D) can be eliminated as well because they’re = they are, and you would not say They are status as a cure-all dates back over 2,000 years... (C) correctly uses the plural possessive their. Their status = the status of the Theobroma cacao seeds. (Note: it is acceptable to say Their status as a cure-all rather than Their status as cure-alls: because the seeds can be understood as a single collective group, a noun disagreement is not created.)
3/25/26
In July of 1848, a group of men and women gathered in Seneca Falls, New York, for the first women’s rights convention held in the United States. Many important figures of the day attended, and among them were: Elizabeth Cady Stanton, Lucretia Mott, and Frederick Douglass.
A. NO CHANGE
B. were—Elizabeth Cady Stanton, Lucretia Mott
C. were Elizabeth Cady Stanton, Lucretia Mott,
D. were Elizabeth Cady Stanton; Lucretia Mott,
A colon must follow a complete, standalone sentence, but Among the important figures of the day who attended were cannot stand by itself as an independent thought. That eliminates (A). (B) simply swaps the colon for a dash, creating the same error. These two types of punctuation can be used interchangeably to introduce a list, but like a colon, a dash used this way must be preceded by a statement that makes sense on its own. Note that the lack of a comma after Lucretia Mott is a distraction here; the comma before and is optional. (D) eliminates that error by removing the unnecessary punctuation after were but creates a new problem by placing a semicolon between Elizabeth Cady Stanton and Lucretia Mott. Although semicolons can acceptably be used to separate the items in a list, they cannot be alternated with commas — only one type of punctuation can be used. That leaves (C), which also eliminates the unnecessary punctuation after were and places only commas between the names in the list.
3/24/26
In 1927, Charles Lindbergh earned instantaneous fame for becoming the first person to fly solo across the Atlantic. In 1925, however, he was an obscure Air Mail pilot, where he was responsible for transporting packages between Chicago and St. Louis.
A. NO CHANGE
B. pilot. Who was responsible
C. pilot, he was responsible
D. pilot responsible
(A) is incorrect because where can only refer to a place. Although the sentence does mention places (Chicago and St. Louis), in this case where is used to refer to an obscure Air Mail pilot, and clearly a pilot is not a place. (B) is incorrect because who cannot begin a sentence that is not a question, so the construction period + who is automatically incorrect. (C) is incorrect because it creates a comma splice — two complete sentences separated by a comma (tipoff: comma + he). (D) is correct because no punctuation is needed between pilot and responsible. Note that this section can be written two ways: he was an obscure Air Mail pilot who was responsible for transporting packages... or he was an obscure Air Mail pilot responsible for transporting packages… Both are equally correct, but only the second option is provided.
3/23/26
Many of us listen to music as a way to calm or energize ourselves. Mona Lisa Chanda and Daniel Levitin, professors at McGill University, have had a look at more than 400 scientific papers on the neurochemical effects of music. Their conclusion was that music truly can boost the body’s immune system, reduce anxiety, and regulate people’s moods.
A. NO CHANGE
B. checked out
C. examined
D. overlooked
Although they make sense in context, had a look at and checked out are both too informal, eliminating (A) and (B). (D) is incorrect because overlooked has the wrong meaning: to “overlook” something is to not notice it, a meaning that does not fit here. (C) is correct because examined is most consistent with the moderately serious tone as well as the meaning of the passage. (Note: even if you interpreted checked out to mean “checked out of a library,” this answer still does not fit as well as (C) — the most logical interpretation is that Chanda and Levitin studied more than 400 papers in order to come to their conclusion, not that they merely accessed them.)
3/22/26
Killer whales are known to live in groups that have unique vocal “dialects” in the wild, they may also copy sounds made by other members of their species, although that ability has not yet been seriously studied.
A. NO CHANGE
B. dialects. In
C. dialect, in
D. dialects; and in
To answer this question, you must focus on the non-underlined portion of the sentence. Although the underlined section in the original version makes sense when considered independently, the comma after wild creates a comma splice — two complete sentences separated by a comma. (C) creates the same error and adds an additional one by placing a comma before a preposition (in). (D) eliminates the comma splice but incorrectly places a semicolon before and. As a coordinating (FANBOYS) conjunction, and can only follow a comma, not a semicolon. That leaves (B), which eliminates the comma splice by using a period to create two separate sentences and moving the phrase in the wild to a more logical position in the second sentence.
3/21/26
Standard computer processors rely on packets, or bits of information: each of the packets represents a single yes or no answer. Quantum processors, on the other hand, don’t work in the realm of yes or no but rather operating in the almost surreal world of yes and no.
A. NO CHANGE
B. would operate
C. operated
D. operate
Because there is nothing to indicate that a tense switch is necessary, the underlined verb must be parallel to the other verbs in the passage. All of the other verbs are in the present tense (rely, represent, don’t), so the underlined verb must be in the present as well. (D) is the only option that contains a present-tense verb, so it is correct.
3/20/26
Although robots have been used in factories for decades, getting them to leave the shop-floor has been no easy task. In manufacturing plants, they carry out pre-ordained, repetitive tasks all day and night. But if they step outside, they are unable to deal with the chaos of the real world, where order and routine are gone. Even the simplest tasks are complicated by the sensors and wires that must follow them around.
Given that all of the choices are true, which one best concludes the paragraph and reaffirms the idea that the real world is disorderly?
A. NO CHANGE
B. unpredictability and vagueness of human interaction.
C. difficulties of creating robots of different sizes.
D. limited amount of energy provided by batteries.
The question asks you to identify the option that “reaffirms the idea that the real world is disorderly” so the correct answer must be negative and have something to do with disorder. (A) and (D) are completely off-topic and can be eliminated. In (C), don’t get distracted by the word difficulties. Although this word is negative, creating robots of different sizes is unrelated to disorder. In contrast, the unpredictability and vagueness of human interaction is directly related to that concept. That makes (B) correct.
3/19/26
Reading foreign books and watching international television are recommended to be a way for people to improve their knowledge of world affairs, but neither is a substitute for spending time in another country.
A. NO CHANGE
B. to be ways
C. as a way
D. as ways
The correct idiomatic phrase is x is recommended as y, eliminating (A) and (B). In addition, reading foreign books and watching international televisions are two separate actions, so they are ways rather than a single way. That eliminates (C) and makes (D) the answer.
3/18/26
Sometimes a symbol can be so familiar that even out of context—different surroundings, different colors and very different materials—it remains immediately recognizable. That’s the case for the five neon-colored tipis that anchor the exhibition “Manifestipi.” Created by ITWE Collective, a trio of artists based in Winnipeg and Montreal, the eight-foot-tall structures made of frosted plexiglass are unmistakeably tipis. Although they look nothing like traditional ones.
A. NO CHANGE
B. Montreal, and the eight-foot tall structures made of frosted plexiglass are unmistakeably tipis, although
C. Montreal the eight-foot tall structures, made of frosted plexiglass are unmistakeably tipis, although
D. Montreal, the eight-foot tall structures made of frosted plexiglass are unmistakeably tipis, although
(A) is incorrect because a sentence that contains only one clause cannot begin with although — a clause that begins with although is always dependent. As a result, although they look nothing like traditional ones is not a sentence and cannot begin after a period. (B) is incorrect because placement of and before the eight-foot tall structures creates a fragment. Comma + and = period, but this type of punctuation cannot be inserted here because Created by ITWE Collective, a trio of artists based in Winnipeg and Montreal is not a sentence. (C) is incorrect because no comma should be placed after structures. This section of the sentence can be written as either eight-foot tall structures that are made of frosted plexiglass, or eight-foot tall structures made of frosted plexiglass. When that is optional and does not appear, no comma should be used in its place. That leaves (D), which correctly uses commas alone after Montreal and tipis to separate the independent clause the eight-foot tall structures made of frosted glass are unimistakeably tipis from the dependent clauses (fragments) before and after it.
3/17/26
Many Parisians hated the Eiffel Tower when it was first erected in 1889. Although they may seem incomprehensible now, that sentiment is perhaps more understandable when you consider that the monument was originally painted red.
A. NO CHANGE
B. it
C. one
D. these
Don’t get fooled into thinking that the underlined pronoun refers to the plural noun Parisians; it does not make any sense to say Although many Parisians may seem incomprehensible now… The only noun to which the underlined pronoun can logically refer is the singular noun sentiment — this is the rare case in which the pronoun precedes its referent. The more typical syntax would read as follows: Although that sentiment (i.e., Parisians’ dislike for the Eiffel Tower) may seem incomprehensible now, it is perhaps more believable when you consider that the monument was originally painted red. That makes the answer (B). One makes no sense in context, and these is plural and creates the same disagreement as they.
3/16/26
Astronomers conducting a galactic census of planets in the Milky Way now suspect most of the universe’s habitable real estate exists on worlds orbiting red dwarf stars, which are smaller but far more numerous than stars like our Sun.
A. NO CHANGE
B. then stars
C. than that of stars
D. as stars
Because the sentence is making a comparison, than rather than then must be used, eliminating (B). (C) is also incorrect because the sentence involves a straightforward comparison between red dwarf stars and stars like our Sun — that of is a possessive construction, and there is no mention of anything belonging to stars. (D) is incorrect because more (far more numerous) must be paired with than, not as. That leaves (A), which correctly uses than to compare stars to stars.
3/15/26
Often advertised to promote health and reduce stress, some doctors warn that dietary supplements can have harmful effects, even though they are easy to purchase.
A. NO CHANGE
B. it is easy to purchase dietary supplements, but some doctors warn that they can have harmful effects.
C. dietary supplements are easy to purchase, yet some doctors warn they can have harmful effects.
D. harmful effects can be had by dietary supplements, even though they are easy to purchase, some doctors warn.
What is often advertised to promote health and reduce stress? Dietary supplements. So dietary supplements, the subject, must be placed after the introductory phrase, at the beginning of the underlined portion. Otherwise, a dangling modifier is created. (C) is the only option that begins correctly, so it is the only possible answer.
3/14/26
From his desk at the European Space Operations Centre in Darmstadt, Germany, space debris analyst Tim Flohrer keeps track of the 23,000 or so catalogued objects currently orbiting the Earth. These objects range from spacecraft and satellites – some working, most not – to rocket parts that they have discarded.
A. NO CHANGE
B. one has
C. we have
D. space agencies have
In the original version, the underlined pronoun is missing an antecedent — there is no plural noun in the passage that they could logically refer to. (B) and (C) both create grammatically acceptable constructions, but neither of these options really makes sense: one and we are used to refer to people in general, but people in general are clearly not discarding rocket parts in space. A much more logical interpretation of the sentence is that space agencies are discarding rocket parts. The use of a noun rather than a pronoun is also much clearer and more specific. (When you are given the choice between a noun and a pronoun, the noun will usually be correct.) That makes the answer (D).
3/13/26
Whatever its origins, brunch seems to have caught on in the United States during the 1930s, supposedly because Hollywood stars whom made transcontinental train trips frequently stopped off in Chicago to enjoy a late morning meal.
A. NO CHANGE
B. who
C. which
D. DELETE the underlined word.
As a rule, who rather than whom must come before a verb. Made is a verb, so who must be placed before it. Which is used to refer to things, but Hollywood stars are people, so (C) can be eliminated. Eliminating the underlined pronoun completely results in an ungrammatical construction (Hollywood stars made transcontinental train trips frequently stopped in Chicago…), so (D) does not work. (B) is thus correct.
3/12/26
The Sahara has not always been a wilderness of sand dunes. German climatologists Rudolph Kuper and Stefan Kröpelin, analyzed the radiocarbon dates of archaeological sites, recently concluded that the region’s prevailing climate pattern changed around 8,500 B.C., with the monsoon rains that covered the tropics moving north.
A. NO CHANGE
B. Kröpelin analyzed
C. Kröpelin, they analyzed
D. Kröpelin, who analyzed
In order to answer this question, you must consider the sentence as a whole — if you just focus on the underlined portion, you will not have enough information. The key to recognizing the error in the incorrect versions is to notice the comma after sites, without a transition afterward. It is incorrect to say, Rudolph Kuper and Stefan Kröpelin analyzed the radiocarbon dates of archaeological sites, recently concluded... The word and should appear after sites to create a grammatical construction. If you don’t notice that problem, however, you might be tempted to pick (B). Because the construction after sites cannot be changed, the underlined portion of the sentence must be changed instead. The only option that creates an acceptable construction is (D): placing comma + who after Kröpelin creates a non-essential clause, which ends after sites. When the clause is crossed out, the sentence still makes perfect sense: German climatologists Rudolph Kuper and Stefan Kröpelin… recently concluded that the region’s prevailing climate pattern?changed around 8,500 B.C., with the monsoon rains that covered the tropics moving north. Even if you do not consider the non-essential clause, (A) is incorrect because it places a comma between the subject (German climatologists Rudolph Kuper and Stefan Kröpelin) and the verb (analyzed). (C) is also incorrect because it is incorrect to place comma + subject pronoun (they) immediately after a subject.
3/11/26
When researchers first found Angamuco, an ancient city in western Mexico built by rivals of the Aztecs, they tried several methods to explore the site, including an on-the-ground approach. Although this strategy compiled a finding of impressive architectural features, they quickly realized it would take them a decade to survey the entire area. As a result, they turned to a laser mapping technique known as light detection and ranging, or LiDAR scanning.
A. NO CHANGE
B. halted
C. yielded
D. adapted
The transition although sets up an opposition between the two halves of the sentence: this strategy _______ a finding of impressive architectural features must convey an idea that contrasts with they quickly realized it would take them decades to survey the entire area. Logically, the first half of the sentence must indicate that the researchers successfully found or identified impressive architectural features. The underlined word must therefore mean something like “resulted in,” or “led to.” The option most consistent with that idea is yielded, so the answer is (C). In (A), the meaning is slightly off (compiled means “amassed”), and this word does not fit grammatically: researchers could compile findings, but strategy cannot be compiled. Halted (stopped) means exactly the opposite of the required word, and adapted does not make sense.
3/10/26
Until the early 1970s, most consumers knew very little about the nutritional content of the prepared foods they purchased. Around that time, however, the dramatic growth in processed food lead to a system of both voluntary and mandatory nutrition labeling.
A. NO CHANGE
B. leads
C. led
D. has lead
This question plays on the confusion caused by the fact that lead has two meanings and can be pronounced in two ways: as a noun, it refers to an element used in pipes and car batteries and is pronounced “led;” as a verb, it is the present-tense third-person form of to lead and is pronounced “leed.” Here, the underlined word is a verb, but the date 1970s indicates that it must be placed in the simple past tense — the sentence is describing a completed action in the past. The present perfect (has + past participle) cannot be used because the action is not continuing into the present. (D) is incorrect both for that reason and because the past participle is the same as the simple past form: led, not lead. (C) correctly provides the simple past form, led.
3/9/26
Although models of planet-forming disks suggest that most star systems should, like the eight planets of our solar system, have roughly circular orbits, in reality, however, only about one-third of the planets identified in other solar systems orbit in a circular fashion.
A. NO CHANGE
B. but in reality,
C. and in reality,
D. in reality,
This is a very long sentence, and the question is essentially testing your ability not to get “lost” in it. Note that if you focus too hard on the underlined portion, there’s no way to figure out the answer — to do so you must back up and consider the beginning of the sentence. The most important thing to notice is the transition although at the beginning of the sentence. Because the first clause contains a transition, a following clause should not also contain a transition (however, but, or and). It does not matter that the transition is used non-essentially here (between two commas) rather than to introduce the clause — regardless of where it appears in the clause, the transition is still unnecessary. Likewise, the fact that howevever and but are used to signal contrasting ideas while and is used to signal similar ideas is irrelevant; the problem involves grammar, not meaning. Only (D) eliminates the unnecessary transition, making it correct.
3/8/26
Vocal imitation is a hallmark of human spoken language, yet in other animals it is strikingly rare. Dolphins and beluga whales are among the few mammals that can copy sounds from other species or each other. A small number of animals can also imitate human speech, like parrots are the most famous example, but some members of the crow family are able to do so as well.
A. NO CHANGE
B. speech such as parrots
C. speech: parrots
D. speech, parrots
(A) and (B) both contain redundancies: the phrase like parrots or such as parrots is used to signal an example, so it is redundant to say the most famous example as well. In addition, both of these answers are awkward to the point of being ungrammatical — they effectively create “jumbled” sentences. (D) is incorrect because placing a comma before parrots creates a comma splice — two complete sentences separated by a comma. (C) correctly uses a colon to introduce the example; grammatically, it has the same function as a period here and can thus serve to separate two complete sentences.
3/7/26
Dogs and humans may be the best of friends today, but research on ancient canine remains shows that the relationship didn’t develop overnight. For long periods of time, people lived in tension with their canine companions. Theirs was a relationship of necessity as well as being convenient.
A. NO CHANGE
B. as well as convenience.
C. and it was convenient.
D. and having convenience too.
The constructions on either side of the transitional word or phrase (as well as, and) must match, or be parallel. The non-underlined side of the transition contains a noun (necessity), so the underlined portion must contain a noun as well (convenience). Both (A) and (C) contain the adjective convenient, so those answers can be eliminated. (D) is incorrect as well because it inserts an unnecessary gerund, having, which disrupts the parallel structure and creates an extremely awkward construction. That leaves (B), which correctly provides the noun convenience alone. You can also think that both items must be able to follow a relationship: it is correct to say a relationship of convenience and a relationship of necessity.
3/6/26
Mushrooms are everywhere — on forest floors, in gardens, and in networks connecting below our feet. The largest organism on Earth is actually a honey mushroom, an underground web, that covers more than 3.7 square miles in Oregon’s Blue Mountains.
A. NO CHANGE
B. web that, covers
C. web covers
D. web covering
As a rule, no comma should be placed either before or after the word that, eliminating both (A) and (B). (C) is incorrect because removing that makes an underground web the subject of the verb covers and creates a comma splice — two complete sentences separated by only a comma. In (D), the -ING word (participle) covering is used as an alternative to that + verb — the two constructions are grammatically equivalent, and neither requires any punctuation. Unlike (A) and (B), however, (D) correctly omits the punctuation and is thus the answer.
3/5/26
While doctors are increasingly dependent on computers, they can also use these devices to help patients in new and important ways. Therefore, electronic medical records can help physicians share information and keep reliable records about which medications a person has been prescribed over a long period of time.
A. NO CHANGE
B. for instance,
C. however,
D. meanwhile,
Start by ignoring the transition and determining whether the statements before and after the transition express similar ideas or different ideas. The first sentence indicates that doctors can use computers to help patients in new and important ways, and the second states that medical records can help physicians share information and keep reliable records, etc. Those are similar ideas. However and meanwhile are used to indicate contrasting ideas, so (C) and (D) can be eliminated. Be careful with (A): the fact that medical records can facilitate the sharing of information is not a result of the fact that doctors can use computers to help patients. Rather, it is an example used to support the more general idea in the previous sentence. That makes the answer (B).
3/4/26
Spiders are among the hardiest creatures in existence: these eight-legged insects live on every continent other than Antarctica and are established in nearly every habitat on Earth, excepting the air and the sea.
A. NO CHANGE
B. exempting
C. to exempt
D. with the exception of
In most cases, shorter answers (to non-grammar/punctuation questions) tend to be correct, but here the answer is actually the longest option: (D). The standard phrase used to indicate that a writer is pointing out an exception is with the exception of — this is a fixed phrase that cannot be replaced by another, similar construction.
3/3/26
A lack of genetic diversity has proven disastrous to many commercial crops. For example, nearly all bananas for sale today are clones of a single parent plant called the Cavendish, initially bred in Great Britain during the nineteenth century. Although Cavendish bananas are hardier than other types of bananas, they are also less flavorful.
A. NO CHANGE
B. Cavendish; initially bred
C. Cavendish: initially bred
D. Cavendish, initially being bred
(B) is incorrect because a semicolon should be used only to separate two complete sentences, and initially bred in Great Britain during the nineteenth century is not a sentence. (C) does not work either: although a colon does not need to be followed by a complete sentence, that is only the case when the colon introduces a list or an explanation, and neither is present here. (D) is incorrect because the use of the gerund being (which almost always signals an incorrect answer) creates a wordy and awkward construction. (A) is correct because it uses a comma alone to separate a complete sentence from the fragment that follows.
3/2/26
From the mechanical humanoids in the 1927 film, Metropolis, to the sinister computer in Stanley Kubrick’s 2001 – A Space Odyssey (1968), movie robots have played a crucial role in shaping people’s attitudes toward these machines for decades.
A. NO CHANGE
B. film, Metropolis
C. film Metropolis,
D. film Metropolis
When a title appears in the middle of a sentence, there are generally only two options: two commas or no commas. (B) and (C) are both distractor answers and can be eliminated immediately. Two commas indicate non-essential information, so to check (A), cross out the title and see whether the sentence makes sense without it: From the mechanical humanoids in the 1927 film…to the sinister computer in Stanley Kubrick’s 2001–A Space Odyssey… No, the sentence does not make sense; we no longer know what the 1927 film is. As a result, the title is essential and no commas should be used, making the answer (D).
3/1/26
The origins of meteorology, or the study of the weather, date back centuries: members of the first agricultural settlements predicted floods based on annual cycles, and inscriptions on ancient tablets referred to different seasons. It was not until just a few hundred years ago, however, that technology became sufficiently advanced to permit any real breakthroughs.
Which choice provides the most relevant and specific information?
A. NO CHANGE
B. noted the connection between thunder and rain.
C. were made with simple tools.
D. described a variety of plants and animals.
The beginning of the sentence indicates that the passage will focus on the study of the weather, and the first example clearly illustrates that idea. The second example, which includes the underlined portion, must do so as well. Different seasons, simple tools, and a variety of plants and animals are all off-topic; only the connection between thunder and rain is directly related to the weather. (B) is thus correct.
2/28/26
Researchers have long believed that planets form in the disc of gas and dust encircling a young star, but the discovery of planets that are very different from our own may have the potential of turning this theory of solar system formation upside down.
A. NO CHANGE
B. in turning
C. for turning
D. to turn
The idiomatic phrase is potential to turn; a preposition + gerund (-ING form) should not be used after this noun. That makes the answer (D).
2/27/26
Bar-tailed godwits have migrated 6,000 miles from Alaska to New Zealand for thousands of years, but a clear picture of their travels have emerged only recently. Today, researchers are beginning to uncover the secrets behind these birds’ remarkable journeys.
A. NO CHANGE
B. has emerged
C. emerge
D. emerging
(A) and (C) contain plural verbs, whereas (B) contains a singular verb, indicating that the question is testing subject-verb agreement. In (D), the gerund emerging creates a fragment, so it can be eliminated immediately. What is the subject of the underlined verb — that is, what has emerged only recently? A clear picture of their travels. Don’t get distracted by the plural noun travels, which appears right before the verb. That noun is part of the prepositional phrase of their travels. The subject is A clear picture or, more precisely, picture. That noun is singular, so a singular verb is required. Only (B) contains a singular verb (has emerged), so it is correct.
2/26/26
Take a look at some of the flowers photographed by Carol Sharp, and you might feel as if you’ve suddenly been transported into an alien world. In Sharps’ pictures, pigmented petals contrast starkly with a black background, while specks of light scatter across the blossoms.
A. NO CHANGE
B. Sharp’s
C. Sharps’s
D. Sharps
The first sentence indicates that the photographer in question has the name Carol Sharp, and the context of the following sentence makes clear that the name must be possessive — it is referring to her photographs. The apostrophe rules that apply to nouns in general also apply to names: to make a name plural, add apostrophe + -s. That makes the answer (B). In (A), -s + apostrophe is used for plural possessive names (e.g., the Sharps’ house = the house belonging to the Sharps). In (B), Sharps’s would be the possessive of the singular name Sharps. And in (D), Sharps would simply be the plural of the last name Sharp (e.g., the Sharps are home tonight = the Sharp family is home tonight).
2/25/26
Formed by volatile chemical compounds that rapidly disintegrate, odors are often fleeting and rapidly disappear, remaining only in people’s memories.
A. NO CHANGE
B. fleeting, disappearing rapidly,
C. fleeting so that they disappear rapidly,
D. fleeting,
By definition, something that is “fleeting” disappears rapidly, so (A), (B), and (C) all contain redundancies. Only (D) eliminates that problem, making it the answer. Note that even if you do not know the definition of fleeting, you can still make a very educated guess that (D) is correct just by looking at the answers. Questions with this type of answer pattern are virtually always testing wordiness, so given three lengthy answers and one short one, the short one will almost certainly be correct.
2/24/26
In 1610, the year Galileo began viewing the sky through the lens of a telescope, he had become the first person to observe Saturn’s rings directly.
A. NO CHANGE
B. has become
C. would become
D. became
The past perfect (had become) should only be used to describe an event in the past that took place before a second event in the past. Logically, however, Galileo could not have become the first person to view Saturn’s rings before he began viewing the sky through a telescope. That eliminates (A). (B) is incorrect because the present perfect (has/have + verb) is used to indicate an action that began in the past and is continuing into the present. As the date 1610 makes clear, however, Galileo’s initial viewing of Saturn’s rings occurred long ago. (C) is incorrect because would is used to refer to a hypothetical action — one that could occur — whereas the sentence is describing an action that did in fact occur. (D) is correct because simple past (became) is used to describe a finished action in the past. Because the other verb in the sentence is in simple past form as well (began), this answer also maintains parallel structure.
2/23/26
Because fairs often attracted large and uncontrollable crowds, permission to hold one could only be granted by royal charter during the Middle Ages.
(A) NO CHANGE
(B) Because they often attracted large and uncontrollable crowds, permission to hold a fair could only be granted by royal charter during the Middle Ages.
(C) Having often attracted large and uncontrollable crowds, it could only be permitted for a fair to be held by royal charter during the Middle Ages.
(D) Often attracting large and uncontrollable crowds, during the Middle Ages fairs could only be permitted by royal charter.
In (B), the introductory clause because they often attracted large and uncontrollable crowds can only describe fairs, the subject. As a result, fairs must be placed immediately after that clause, following the comma. It is not placed there, however, so this answer creates a dangling modifier. (C) and (D) contain the same error: both begin with introductory phrases that describe fairs, but neither places that word immediately afterward. The original version avoids the dangling modification by placing fairs at the beginning of the sentence. (A) is thus correct.
2/22/26
In the last few years, some towns in Iceland, India and China have experimented with “floating” cross walks. They rely on three-dimensional optical illusions for their effectiveness, they make the crossings appear to be floating above the ground, thus causing drivers to slow down.
A. NO CHANGE
B. Relying on
C. These rely on
D. Although they rely on
If you just focus on the beginning of the sentence, then the construction in the original version seems perfectly acceptable; the problem isn’t apparent until later in the sentence. The comma after effectiveness creates a comma splice: two complete sentences separated by a comma. Because they make cannot be changed, the construction at the beginning of the sentence must be changed instead. (C) creates the exact same error as (A) — they and these are grammatically interchangeable, so this answer does nothing to address the actual problem. (D) is grammatically acceptable — placing although at the beginning of the sentence makes the first clause dependent and thus able to be separated from the rest of the sentence by a comma — but it creates an illogical relationship: there is no contrast between the fact that “floating” cross walks rely on optical illusions and that they appear to float. (B) is correct because the use of an -ING word (relying) rather than subject + verb (they rely) creates a dependent clause without disrupting the logic of the sentence and makes the comma after effectiveness acceptable.
2/21/26
If you had stepped off a plane in Bogota, Colombia, in the 1960s, one of the first things you would of probably saw outside the airport was a giant billboard. In a slightly menacing tone, it said, “Coffee rust is the enemy. Don’t bring plant materials from abroad.”
A. NO CHANGE
B. would of probably seen
C. would have probably saw
D. would have probably seen
As a rule, would (along with could, should, and might) must be followed by have, not of — this very common error plays on the fact that the two words are pronounced identically. Because the correct answer must contain have, both (A) and (B) can be eliminated. (C) can be eliminated as well because any form of the verb have must be followed by the past participle (seen) rather than the simple past (saw). (D) provides the correct form and is thus the answer.
2/20/26
Enabling workers as well as pedestrians to walk in climate-controlled comfort even when temperatures drop well below zero, and the Minneapolis Skyway System is an interlinked collection of enclosed footbridges that connect various buildings over 11 miles of downtown Minneapolis.
A. NO CHANGE
B. zero, but the Minneapolis Skyway System
C. zero, the Minneapolis Skyway System, which
D. zero, the Minneapolis Skyway System
(A) and (B) are incorrect because comma + and & comma + but are used to separate two complete sentences; however, the statement before the comma (Enabling workers as well as pedestrians to walk in climate-controlled comfort even when temperatures drop well below zero) is not a sentence. (C) fixes the original problem but creates a new one: it turns the main clause into a fragment. The addition of comma + which “removes” the verb is from its intended subject, the Minneapolis Skyway System, and makes which the subject. As a result, the clause lacks a main verb. The only grammatically acceptable option is (D), which correctly places a comma alone between a fragment and the full sentence that follows.
2/19/26
Cheetahs are known for their impressive running speeds, which can reach more than 60 miles per hour. Lions are more powerful. However, they are not nearly as fast on their feet.
Which of the following would NOT be an acceptable alternative to the underlined portion?
A. powerful, but they are
B. powerful; they are, however,
C. powerful but
D. powerful, but are
The question is asking which option would NOT be an acceptable alternative to the underlined portion, so the correct answer must be grammatically incorrect. (A) can be eliminated because comma + but is grammatically equivalent to period + However, which appears in the passage itself. (B) can be eliminated because this answer is also grammatically equivalent to the version in the sentence — the words are just rearranged. A period is identical to a semicolon, and however is merely moved to a later point in the clause. In terms of meaning, there is no difference between beginning a sentence/clause with a transition, and surrounding that transition with commas later on in the sentence. Both versions indicate that the transition is connecting that statement to the previous one. (C) is okay as well because there is no reason to use any punctuation before but. A semicolon or period is never correct before this word, and comma + but is identical to a period. It would make no sense to say Lions are more powerful. Not nearly as fast on their feet. That leaves (D), which incorrectly places a comma before but. Again, comma + but = period, and it does not make sense to plug in a period: Lions are more powerful. Are not nearly as fast on their feet. Because (D) is NOT acceptable, it is correct.
2/18/26
The “Ring of Fire” is a string of volcanoes, earthquake sites, and tectonic plates around the Pacific. It spreads across 25,000 miles, from the southern tip of South America all the way to New Zealand. Roughly 90% of all earthquakes occur in the ring, with the majority of those quakes resulting from a small number of locations where plates are exceptionally active.
A. NO CHANGE
B. along with
C. in addition to
D. and
To answer this question, you need to focus on the section of the sentence that comes after the underlined portion. The most important thing to notice is that it contains an -ING word (resulting) rather than a conjugated verb (result). If you know that the construction with + -ING can be used as an alternative to and + verb (e.g., and the majority of quakes result from…), then you can focus on (A) from the start. Both (B) and (C) can be eliminated because they create awkward, illogical constructions when plugged into the sentence. Note that although with + -ING is a common idiomatic construction, along with cannot be used as an alternative. (D) is incorrect because a clause that begins with a conjunction (and) and contains a subject (the majority) must contain a verb rather than an -ING word. That leaves (A), which is correct.
2/17/26
At least in moderate amounts, stress may not be as harmful as we think. In fact, research suggests that people who view stress as a form of motivation perform better under pressure and have less health complaints than those who view stress as debilitating.
A. NO CHANGE
B. less health complaints then
C. fewer health complaints than
D. fewer health complaints then
To answer this question, you need to know that less is used to modify singular nouns, whereas fewer is used to modify plural nouns. Health complaints is plural, so fewer should be used. That eliminates (A) and (B). (D) can be eliminated as well because then is a synonym for next — than is used for comparisons. (C) provides the correct form, making it the answer.
2/16/26
In a downtown park in the city of Kumamoto on Kyushu, the southwestern-most of Japan’s main islands, a group of locals can be found trying consistently to complete what could be called the world’s hardest jigsaw puzzle. It’s a problem so large that the pieces cover the size of a football field, a riddle so challenging that it will take them nearly 20 years to complete.
Which choice most strongly emphasizes that the group is focusing intently on the puzzle?
A. NO CHANGE
B. painstakingly
C. excitedly
D. impulsively
The key phrase in the question is focusing intently, so the correct answer must be consistent with the idea of intense concentration. Consistently just means “on a regular basis” — it has nothing to do with the amount of focus an action is performed with. (A) can thus be eliminated. If you don’t know what painstakingly means, skip it and work through the other options. Excitedly might seem like a possible answer, but be careful: being excited about something is not necessarily the same thing as paying very close attention to it. The two things can be related, but one does not automatically imply the other. Impulsively means “without warning,” or “on the spur of the moment.” Again, this is unrelated to the idea of intense focus. That leaves (B). To do something painstakingly is to do it with enormous care and attention to detail, i.e., to focus on it intently. That makes (B) the answer.
2/15/26
Citrus trees are among the most widely cultivated fruit trees in the world, but until recently, their history has been unclear. Seeking to obtain a better understanding of where these trees originated, the genomes of more than 50 varieties of citrus fruit were analyzed by researchers in the United States and Spain, from the Chinese mandarin to the Seville orange.
A. NO CHANGE
B. an analysis of the genomes of more than 50 varieties of citrus fruit was performed in the United States and Spain by researchers,
C. more than 50 varieties of citrus fruit had their genomes analyzed by researchers in the United States and Spain,
D. researchers in the United States and Spain analyzed the genomes of more than 50 varieties of citrus fruit,
The key to answering this question is to consider the answer in relation to the beginning, non-underlined portion of the sentence. Approached that way, this question is much simpler than it appears. Who was seeking to obtain a better understanding of where these (citrus) trees originated? Logically, it could only be scientists. So scientists, the subject, must be placed at the beginning of the correct option. Placing the genomes, an analysis, or more than 50 varieties in the spot creates a dangling modifier. That makes (D) the only possibility. Note that this option also fixes the modification at the end of the sentence. The last phrase, from the Chinese mandarin to the Seville orange, refers to types of citrus fruit, so citrus fruit must be placed at the end of the correct option, right before the comma.
2/14/26
Creativity is often defined as the ability to come up with new and useful ideas. Like intelligence, it can be considered a trait that everyone, not just creative geniuses possesses in some capacity.
A. NO CHANGE
B. geniuses that possess
C. geniuses possesses,
D. geniuses, possesses
The key to answering this question is to recognize that the verb possesses belongs to the subject everyone, which appears in the non-underlined portion — possesses is singular and cannot agree with the plural noun geniuses. The only way to make everyone the subject of possesses is to create a non-essential clause. The first comma appears after everyone, and the second comma must appear before possesses. When the clause is crossed out, the remaining sentence makes perfect sense: …it can be considered a trait that everyone…possesses in some capacity. That makes the answer (D). When the comma is placed after possesses, as is the case in (C), the remaining sentence does not make sense: ...it can be considered a trait that everyone… in some capacity. (A) and (B) are in part incorrect because they do not create a non-essential clause at all. In (A), the singular verb possesses also directly disagrees with the plural subject geniuses. Although the phrase geniuses that possess in (B) is acceptable on its own, it creates an awkward and ungrammatical construction when it is plugged into the sentence.
2/13/26
The origins of saffron are a mystery: competing claims place the wild plants beginning’s in regions along a wide swath of land, from Greece in the eastern Mediterranean all the way to Central Asia.
A. NO CHANGE
B. plants beginnings
C. plant’s beginnings
D. plant’s beginnings’
Don’t get too thrown off by all the different combinations of plural (-s only) and possessive (apostrophe) forms. When two nouns are underlined, the usual pattern is that the first noun has an apostrophe but the second does not. As a general rule, when two nouns are placed next to each other without a comma between them, the first is possessing the second. That eliminates (A) and (B). To confirm that the second noun does not require an apostrophe as well, look at the word after beginnings. In is not a noun, so beginnings does not require an apostrophe. That eliminates (D), leaving (C). wild plants beginnings = beginnings of the wild plant, i.e., the origins of saffron.
2/12/26
At any given time, the vast majority of the volcanic activity on Earth isn’t occurring in continent-covering floods of magma or in explosions like the one at Mount St. Helens. Rather, it’s on the seafloor, where the tectonic plates are spreading apart. As the Earth’s crust splits, the mostly solid mantle layer raises to fill the space created.
A. NO CHANGE
B. raises for filling
C. rises to fill
D. rises in filling
When used as a verb, raise must either be followed by a noun (e.g., they raise chickens on their farm) or used as part of a passive construction (e.g., wages were raised). It is incorrect to say x raises — when no noun is present right after the verb, the correct form is rises. In this case, the underlined verb is not followed by a noun, so rises should be used. In addition, this verb must be followed by an infinitive (to fill) rather than in + -ING. That makes the answer (C).
2/11/26
The fight between the Earth’s magnetic field and the solar wind produces some surprising effects, including: the Aurora, or the Northern and Southern Lights, which can appear when the highly charged particles from the sun hit the Earth’s atmosphere, causing a glowing green light display.
A. NO CHANGE
B. effects, including the Aurora, or the Northern and Southern Lights,
C. effects, including the Aurora, or the Northern and Southern Lights;
D. effects including the Aurora or the Northern, and Southern Lights
Although colons are used to introduce lists and explanations, they should not be placed after the word including. The reason is that a colon must be preceded by a sentence that can stand on its own as a complete thought, a construction that is essentially impossible when a statement ends with including. Here, for example, The fight between the Earth’s magnetic field and the solar wind produces some surprising effects, including clearly cannot stand by itself. That eliminates (A). (C) is incorrect because when this answer is plugged in, the semicolon is placed between a sentence and a fragment rather than two complete sentences. Note that the semicolon is immediately followed by which, a word that cannot begin a sentence. (D) is incorrect because including should be set off by a comma and because no comma should be placed before the word and. Comma + and = period, and it makes absolutely no sense to say …effects including the Aurora or the Northern. Southern lights which appear.… (B) appropriately uses a comma to set off including, and the commas around or Northern and Southern Lights also correctly signal that this phrase can be removed from the sentence without disrupting its basic grammatical structure: The fight between the Earth’s magnetic field and the solar wind produces some surprising effects, including the Aurora…which can appear when the highly charged particles from the sun hit the Earth’s atmosphere, causing a glowing green light display.
2/10/26
It is well known that seismic activity can affect hydrologic activity—that is, the movement of water. In the aftermath of nearby large earthquakes, dry streams can start flowing, well levels can go up or down, and eruptions of geysers sometimes occur.
Which choice best maintains the pattern already established in the sentence?
A. NO CHANGE
B. sometimes geysers will erupt.
C. geysers can sometimes erupt.
D. there is an eruption of geysers sometimes.
The first two items in the list both contain the structure x can do y (dry streams can start flowing, well levels can go up or down), so the third item must be presented in that structure as well. The fastest way to answer this question is to notice that (C) alone contains the word can. That makes it the only possible answer.
2/9/26
Generally speaking, solar eruptions are caused by a sudden, violent rearrangement of the Sun’s magnetic field. At a deeper level, however, the process is controlled by two types of structures that form in the magnetic field of the Sun: ropes and cages. The rope is confined within the magnetic cage. If the cage is strong, it can contain the rope’s contortions, but when the cage is weak, an eruption can cause it to rip through.
As it is used in the last sentence, the word “contain” most nearly means
A. encompass
B. restrict
C. exclude
D. comprehend
In the last sentence, the word but sets up a contrast between what happens when the cage is weak (an eruption can cause it to rip through) and what happens when the cage is strong. Logically, the sentence must be saying that when the cage is strong, it must prevent the rope from ripping through, or cause it to remain within the cage — in other words, it must restrict the rope. The answer is therefore (B). Don’t get distracted by encompass — this is a literal synonym for contain, but it doesn’t have the same connotation of preventing something from breaking through. Be careful with (C) as well: exclude implies that the cage stops the rope from contorting at all, not that it limits the rope’s movement. In addition, this word has the wrong connotation: it implies that something or something is not allowed to participate in a group or event, a meaning that does not make sense here. Comprehend does not fit at all.
2/8/26
Scientists have found that animals across the spectrum have a keen sense of quantity, able to distinguish not just bigger from smaller or more from less, but two from four, four from ten, and forty from sixty. Orb-weaving spiders, for instance, keep a tally of how many silk-wrapped prey items are stashed in the “larder” segment of their web. In one experiment, scientists removed the items. Despite this, the spiders spent time searching for the stolen goods in direct proportion to how many separate items had been taken.
A. NO CHANGE
B. Subsequently,
C. However,
D. Likewise,
Start by ignoring the transition already in the passage, and focus on determining the relationship between the sentence begun by the underlined transition and the sentences before — to make sense of this question, you must consider the last sentence in terms of the full paragraph. Essentially, the passage is discussing the fact that animals are capable of identifying specific quantities, and orb-weaving spiders are used as an example of a species that can apparently keep track of specific numbers. The “experiment” is then cited to explain how scientists determined orb-weaving spiders possessed that ability. The last sentence of the passage describes the result of the experiment: the spiders’ behavior suggested they could in fact count. Given that context, the correct transition must indicate that the last sentence is continuing the idea presented before it. Despite this and However are used to introduce contrasting ideas, so (A) and (C) can be eliminated. Even though likewise is used to introduce similar ideas, it does not fit here. This transition indicates that two things are similar, or like one another, which is not the case here — the last sentence focuses on the spiders’ behavior, whereas the previous sentence describes the scientists’ action. The only option that makes sense is subsequently, which means “next” or “then.” Logically, the spiders spent time searching for the stolen goods after the scientists removed them. That makes (B) the answer.
2/7/26
Whatever the truth behind the origins of macaroni and cheese, this humble dish has become an ultimate comfort food in many cultures and countries, each with their own favored variations.
A. NO CHANGE
B. they’re
C. its
D. its’
Don’t get distracted by the plural nouns countries and cultures — the underlined pronoun refers to each, which is singular (each is short for each one) and thus requires a singular pronoun. Their and they’re are forms of the plural pronoun they, so (A) and (B) can be eliminated. (D) can be eliminated as well because its‘ does not exist. That leaves (C), which correctly provides the singular possessive form, its.
2/6/26
All frozen water consists of molecules arranged in a hexagonal structure similar to a honeycomb; however, the ice coating bobsled tracks or the firm, flattened snow of a ski course is precisely shaped and conditioned, optimizing the properties of this frosty form of water.
A. NO CHANGE
B. firm, flattened, snow of a ski course
C. firm flattened snow, of a ski course
D. firm, flattened snow of a ski course,
All of the answers might look similar initially, so try to avoid letting them blur together, and instead focus on finding the differences in the placement of the commas. There are a few key features here that can help you eliminate incorrect answers quickly. (B) can be crossed out because commas can be placed only between adjectives (firm, flattened), never between an adjective and the noun it modifies (flattened, snow). If you know the “no comma before a preposition rule,” (C) can be eliminated because a comma is placed before the preposition of. Note that the lack of a comma between firm and flattened is only a distraction here. Be careful with (D): when this answer is plugged in, a comma is placed between the subject and the verb (the firm, flattened snow of a ski course, is precisely shaped...). This construction is never correct, so (D) can be eliminated too. That leaves (A), which correctly places a comma between the two adjectives (firm and flattened) and does not contain any additional, unnecessary punctuation.
2/5/26
The appearance of tiny cracks in concrete can be harmful because they provide an easy route of entry in for liquids and gasses – and the harmful substances they contain. Even a slender breach the width of a hair can let enough water in to undermine the concrete’s integrity. For example, micro-cracks can allow water and oxygen to infiltrate and then corrode steel supports, causing a structure to collapse.
If the author were to delete the underlined portion, the paragraph would primarily lose
A. a detail that emphasizes the dangerous consequences of tiny imperfections in concrete.
B. a claim that shifts the paragraph away from the discussion of harmful substances.
C. a comment that introduces the main idea of the paragraph.
D. irrelevant information that distracts from the focus of the paragraph.
Although the question appears to ask about the paragraph without the underlined phrase, this wording is somewhat misleading. In reality, the question is asking what sort of information the underlined phrase contains. As a result, you should start by focusing on the phrase itself. The first thing to notice is that it contains a description: it illustrates just how small a “slender breach (crack)” can be. A description isn’t a “claim,” as (B) states. It’s also smack in the middle of a sentence, so it can’t really be a comment introducing a main idea, as (C) indicates. The fact that the phrase provides detail can point you to (A). Something that is the width of a hair is very, very small. The next sentence indicates that these tiny cracks can [cause] a structure to collapse, and so the underlined description emphasizes just how seriously concrete can be affected by apparently minuscule flaws. Far from being irrelevant to the point of the paragraph, this information serves to reinforce it. That eliminates (D) and makes the answer (A).
2/4/26
Maglev—or magnetic levitation—trains, which use magnets to lift a train above its rails, reducing friction, and increasing possible speeds are already in operation. The most famous one takes passengers from downtown Shanghai to the city’s airport at 270 miles per hour. But of the plans to make a maglev even faster by putting it in a vacuum tube, Hyperloop One is the most advanced.
A. NO CHANGE
B. reducing friction, and to increase possible speeds,
C. reducing friction and increasing possible speeds,
D. reduce friction, and increasing possible speeds
This is a question that initially seems to be testing parallel structure in list form but then throws in a twist. The non-underlined portion of the sentence contains the first item (to lift a train above its rails), so the second and third items would logically be (to) reduce and (to) increase. The problem is that there is no option with this construction. (B) and (D) contain various combinations of -ING words, verbs, and infinitives, none of which works grammatically, so they can be eliminated. That leaves (A) and (C), the only answers that contain verbs in parallel form (reducing, increasing). (C) is correct because it creates a non-essential clause rather than completing a list. You can check this out by crossing the clause out of the sentence: Maglev trains, which use magnets to lift a train above its rails,…are already in operation. The sentence that remains makes grammatical sense, so this answer is acceptable. (A) does not work because there is no comma after speeds, so this answer cannot function as a non-essential clause. As a result, it creates yet another non-parallel list.
2/3/26
A new type of vaccine, which could become available in the United States over the next few years, is made by growing viruses in cultures of animal cells rather than with chicken eggs.
A. NO CHANGE
B. in
C. to
D. from
The sentence contains the basic structure A new type of vaccine is made by growing viruses in x rather than ______ y, so the prepositions on either side of the phrase rather than must be the same in order to create a parallel construction. The preposition on the non-underlined side of the sentence is in, so the same preposition must be used in the underlined portion as well. That makes the answer (B).
2/2/26
A factory needs robots to perform repetitive tasks at high volume 24 hours a day. The most common robots are large industrial machines dedicated to specific processes that run independently and can be more than six feet tall and 30 feet long.
A. NO CHANGE
B. processes, which run independently and can be
C. processes. These machines run independently and can be
D. processes; running independently and being
The original version contains a misplaced modifier: the phrase that run independently and can be [more than six feet tall and 30 feet long] should logically describe large industrial machines but instead describes specific processes — clearly processes cannot be six feet tall and 30 feet long. (B) contains the same error; this answer just uses which instead of that to begin the modifying phrase. (D) is incorrect because a semicolon must be used to divide two complete sentences, and running independently and being more than six feet tall is not a sentence. As a shortcut, a semicolon should not be followed by an -ING word. Although it is longer than the other answers, (C) is correct because it eliminates the misplaced modification by making clear that more than six feet tall and 30 feet long describes industrial machines and uses a period to divide two complete sentences.
2/1/26
Sleep-inducing substances may come from the process of making new connections between neurons. Sleep researcher, Chiara Cirelli, suggests that since making these connections, or synapses, is what our brains do when we are awake, maybe what they do during sleep is scale back the unimportant ones, removing the memories or images that don’t fit with the others, or don’t need to be used to make sense of the world.
A. NO CHANGE
B. researcher, Chiara Cirelli
C. researcher Chiara Cirelli,
D. researcher Chiara Cirelli
When it comes to commas with names in the middle of a sentence, there are essentially two options: no commas (essential) or two commas (non-essential). A comma only before the name is always incorrect, and although a comma only after the name may in extremely rare cases be acceptable, this is not an exception that you normally need to worry about. The easiest way to check whether commas are necessary is to cross the name out and read the sentence without it: Sleep researcher…suggests that since making these connections, or synapses, is what our brains do when we are awake… No, that does not make sense. Although it may be grammatically acceptable in the most technical sense, it not only sounds completely wrong but it also does not tell us who the sleep researcher is. The name is therefore essential for the logic of the sentence. As a result, no commas should be used, making (D) correct.
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