GMAT Sentence Correction: Subject-verb agreement and pronoun-antecedent agreement
Among the more basic and familiar types of Sentence Correction errors are subject-verb agreement and pronoun-antecedent agreement. A singular subject needs verbs of the singular form. A plural subject needs verbs of the plural form.
The elephant bathes. (not “The elephant bathe.”)
Elephants bathe. (not “Elephants bathes.”)
When an elephant bathes, it uses its trunk to spray water over its back.
When elephants bathe, they use their trunks to spray water over their backs.
When the subject is an elephant, we need the singular pronouns it and its.
When the subjects are elephants, we need the plural pronouns they and their.
It is true that the pronouns they and their are used now more than ever as singular pronouns. The GMAT Official Guide only comments that this issue is “complex and evolving.” But even before the usage of they and their began evolving, it was normal and accepted to say something like, “Who left their headlights on?” You would get funny looks if you said, “Who left his headlights on?” or even “Who left his or her headlights on?”
Sentence Correction questions won’t test you on the evolving singular usage of they and their for humans. However, these questions frequently introduce pronoun-antecedent agreement errors or subject-verb agreement errors in sentences about animals, as in the examples above.
Examples of Agreement Errors
GMAT Sentence Correction Question
Here’s one such question from the Official Guide:
Foraging at all times of the day and night, but interspersing their feeding with periods of rest that last between one and eight hours, a sperm whale could eat so much as a ton of squid a day.
(A) last between one and eight hours, a sperm whale could eat so
(B) between one and eight hours, sperm whales can eat as
(C) between one to eight hours, sperm whales could eat as
(D) from one to eight hours, sperm whales could eat so
(E) from one to eight hours, a sperm whale can eat so
Since the first part of the sentence uses the plural possessive pronoun their, the underlined portion must refer plurally to sperm whales, not singularly to a sperm whale. This rules out answer choices A and C. Choices C and D have idiomatic problems, but they also use could instead of can, making it sound like this is merely a hypothetical possibility for sperm whales, when the sentence actually means to talk about something sperm whales really do. The correct answer is B.
GMAT Sentence Correction Question
Here’s another GMAT sentence correction question involving animals:
In California, a lack of genetic variation in the Argentine ant has allowed the species to spread widely; due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits the spread of this species in its native Argentina.
(A) due to their being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits
(B) due to its being so genetically similar, the ant considers all its fellows to be a close relative and thus does not engage in the kind of fierce intercolony struggles that limit
(C) because it is so genetically similar, the ant considers all its fellows to be close relatives and thus does not engage in the kind of fierce intercolony struggles that limits
(D) because they are so genetically similar to one another, the ants consider all their fellows to be close relatives and thus do not engage in the kind of fierce intercolony struggles that limit
(E) because of being so genetically similar to one another, the ants consider all their fellows to be a close relative and thus do not engage in the kind of fierce intercolony struggles that limits
Some Sentence Correction questions are difficult just because they go on forever and wear down your attention. Let’s talk about the observations you should make as you process this one.
The given version of the sentence first mentions “the Argentine ant.” Given this singular reference, we would expect the rest of the sentence to use the singular pronouns it and its, not the plural pronouns they and their. But this is a long, complex sentence.
There is a semicolon right before the underlined portion, creating a new independent clause. Then there is a plural reference to “the ants.” This makes the use of the plural possessive pronoun their in the underlined portion correct.
The given version of the sentence actually doesn’t have any pronoun-antecedent agreement problems. But it does have an agreement issue involving singularity and plurality. It says that “the ants consider all their fellows (plural) to be a close relative (singular)…” This doesn’t work. All the fellow ants can’t be one close relative.
Answer choices C and D are the only ones that fix this problem by using the plural “close relatives” instead of the singular “a close relative.” But C doesn’t make any sense because it begins by saying, “because it is so genetically similar, the ant . . .” So genetically similar to what?
The idea is not that the Argentine ant is so genetically similar to some other ant species; it is that the Argentine ants in different California colonies are so genetically similar to one another. D is the correct answer choice.
Another way to find the correct answer in sentence correction questions
That was still somewhat involved, and as usual on Sentence Correction questions, there is another, better way. Did you notice a subject-verb agreement issue at the very end of the underlined portion? We are told that the ants “do not engage in the kind of fierce intercolony struggles that limits . . .” If the subject is the plural struggles, then the verb should be limit, not limits.
One might mistakenly argue that the subject is actually the singular kind from the prepositional phrase “the kind of struggles,” but kind here does not function substantively. The struggles themselves are the real subject. So we need an answer choice that ends with limit, not limits.
Since it’s very easy to check the beginning or the end of long answer choices (checking some word or phrase in the middle would take longer), this approach is fastest. We can quickly narrow down our selection to B and D – the only choices that end with limit. Again, D is the one that begins with the right idea of the ants’ genetic similarity to one another, so it is the correct answer.
GMAT Sentence Correction Question
Here’s one more agreement problem involving animals. Or is it an animal?
Starfish, with anywhere from five to eight arms, have a strong regenerative ability, and if one arm is lost it quickly replaces it, sometimes by the animal overcompensating and growing an extra one or two.
(A) one arm is lost it quickly replaces it, sometimes by the animal overcompensating and
(B) one arm is lost it is quickly replaced, with the animal sometimes overcompensating and
(C) they lose one arm they quickly replace it, sometimes by the animal overcompensating,
(D) they lose one arm they are quickly replaced, with the animal sometimes overcompensating,
(E) they lose one arm it is quickly replaced, sometimes with the animal overcompensating,
Since this sentence begins with the plural Starfish, we would expect to see the plural pronouns they and their. This makes the singular pronoun it in the phrase “it quickly replaces it” in the given version incorrect. However, all of the answer choices later refer singularly to the animal. How did this shift from the plural Starfish to the single the animal occur?
While the plural Starfish in the introduction needs plural pronouns, we don’t really want to talk about multiple starfish losing one arm. We want to talk about a starfish losing one arm. This is how the sentence ends – talking about “the animal,” the single starfish, sometimes overcompensating and growing an extra arm or two.
So choices C, D, and E don’t work. It is illogical to talk about plural starfish (they) collectively losing one arm, and it doesn’t match the later singular reference to “the animal.”
The only way to make the parts of this sentence work together is to use the passive voice when talking about the replacement of the lost arm, as answer choice B does.
Starfish, with anywhere from five to eight arms, have a strong regenerative ability, and if one arm is lost it is quickly replaced, with the animal sometimes overcompensating and growing an extra one or two.
The passive voice refers to the lost arm being replaced without explicitly naming the subject doing the replacing. But we can infer some of this tacit information like this:
Starfish, with anywhere from five to eight arms, have a strong regenerative ability, and if one arm (of a starfish) is lost it is quickly replaced (by the starfish), with the animal sometimes overcompensating and growing an extra one or two.
This makes everything work. Agreement is a simple concept, but complex grammatical scenarios can arise. Always look for a way to make the references consistent.
To learn more about another common error, check out our next article on “Common Sentence Correction Errors: Verb Forms and Parallelism.“
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Contributor: Elijah Mize (Apex GMAT Instructor)