Explanation -

3/25/25

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.

3/24/25

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.

3/23/25

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.)

3/22/25

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.

3/21/25

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.

3/20/25

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.

3/19/25

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.

3/18/25

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.

3/17/25

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.

3/16/25

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.

3/15/25

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.

3/14/25

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).

3/13/25

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.

3/12/25

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.

3/11/25

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.

3/10/25

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.

3/9/25

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.

3/8/25

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.

3/7/25

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.

3/6/25

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.

3/5/25

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).

3/4/25

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.

3/3/25

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.

3/2/25

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).

3/1/25

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.

2/28/25

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).

2/27/25

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.

2/26/25

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).

2/25/25

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.

2/24/25

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.

2/23/25

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.

2/22/25

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.

2/21/25

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.

2/20/25

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.

2/19/25

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.

2/18/25

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.

2/17/25

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.

2/16/25

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.

2/15/25

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.

2/14/25

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.

2/13/25

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.

2/12/25

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).

2/11/25

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.

2/10/25

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.

2/9/25

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.

2/8/25

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.

2/7/25

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.

2/6/25

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.

2/5/25

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).

2/4/25

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.

2/3/25

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).

2/2/25

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.

2/1/25

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.

Explanation