Here are some examples of how to work through Error-Identification questions.
Example #1:
In 1965, Betty Friedan’s publication of The Feminine
Mystique has marked a turning point that resulted in
improved labor rights and working conditions for
women. No error
Strategy:
The big “clue” in this question is the date 1965, which tells us that this is probably a tense question. So that means we’re going to start by checking the tenses of any underlined verbs, which in this case means choice (B), “has marked.”
Now, any finished event or action in the past (e.g. the publication of The Feminine Mystique, which occurred once) must be referred to by a verb in the simple past: “marked,” not “has marked.”
So the answer is (B). Notice that working from the clue made it unnecessary to even check any of the other answers.
Example #2
The findings of an astronomy team overseen by
researchers at Stanford University has confirmed many
of Einstein’s strangest predictions about the nature
of gravity. No error
Strategy:
Since there’s no obvious clue in this sentence, we’re going to start by looking for the option most likely to be incorrect. In this case it’s choice (B). it could either be a subject-verb agreement question (because you can say either “has confirmed” or “have confirmed”) OR a tense question.
Since there’s no date or time period, however, we know right away that tense probably isn’t the issue. So we’re going to check the subject. It’s “findings,” which is plural; “has” is singular, so right there you have your answer.
This is a classic subject — prepositional phrase — verb question. It’s tricky, and so it would probably show up close to the end of a section.
Example #3
The snakehead fish, a rapidly reproducing predator, has so
voracious an appetite that it can wipe out entire schools of
fish and destroy entire ecosystems when placed outside
its native habitat. No error
Strategy: Again, here, there’s no obvious error, so we’re going to check in order of what’s most likely to be wrong.
The first thing we notice is the word “its.” That’s usually a very dangerous word in this section, so we’re going to start with it. In this case, it refers to “the snakehead fish,” which is also singular, so “it” actually checks out.
When a word that is commonly wrong turns out to be right, that’s a hint the answer might be “No error.” But we have to check out everything else just to be sure.
We’re going to check choice (D) next because it’s a verb in the present tense and is therefore also a top error candidate.
Choice (D): there’s nothing to suggest that “destroy” is in the wrong tense; it’s also parallel to “wipe out” (it can wipe out…it can destroy), which means there’s no problem.
Now we move to the other options.
Choice (A): “rapidly” is adverb, so we stick in the adjective: “a rapid reproducing predator.” No — an adverb is necessary to modify “reproducing,” which functions as an adjective.
Choice (B): “so” might sound a little funny, but it’s half of a word pair, and here is correctly paired with “that.” It’s fine.
Which means that we’ve demonstrated the answer must be (E).