Indoor air pollution can threaten the health of closely confined farm

With modal verbs, you use the base form of the main verb even if the subject is singular.

Following are correct usage:

Pollution impairs the quality...
Pollution perhaps impairs the quality... (perhaps is an adverb)
Pollution may impair the quality... (may, a modal verb is used)

Air pollution (singular) would normally go well with impairs (singular). The may is the reason that we see an impair in the correct option (as gvij2017 pointed out).
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IMO E: may also impair the quality of such products as
impair plural product andsuch asfor eggs , poultry

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

(A) perhaps as well impairs the quality of such farm products like
Incorrect - such as is used for examples
(B) perhaps as well impairs the quality of such farm products as
Correct
(C) perhaps also impairs the quality of such farm products like
same error as A
(D) may also impair the quality of such farm products like
same error as A and subject- verb error (see option E)
(E) may also impair the quality of such products as
Subject Indoor air pollution - singular, so impair should be impairs

P.S. - Please do correct me, if my reasoning seems to be faulty.

Hi,

I also made the same mistake when I was at your stage.

We don't use s/es with the verb when we use model verb.

Hey gvij2017, thanks for your reply.
Could you please elaborate which modal verb you are referring to in context of the question? Also, what is the correct usage of it?

may, can, should, could, would, might etc.

My approach - it should clearly be impair because 'air pollution' is one entity. A, B, C is eliminated

Out of D and E, shouldn't it clearly state "farm products?". I think only reason why D goes out would be

[such --- like] is illegal construction
[such --- as] is right

Official Explanation

Agreement; Diction

In the sentence as written, the phrase as well is used incorrectly as a substitute for also. Furthermore, the incorrect construction such . . . like is used rather than such . . . as.

A. This choice is incorrect for the reasons mentioned above.
B. This choice incorrectly uses as well as a substitute for also.
C. This choice correctly uses also, but it uses the incorrect construction such . . . like.
D. This choice correctly uses also, but it uses the incorrect construction such . . . like.
E. Correct. This choice correctly uses the construction such . . . as and correctly uses also instead of as well.

The correct answer is E.

Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

So here if we pay close attention we have and, which triggers parallelism . In the 1st non underlined Part we have Can threaten so we need parallel verb to that, based on that

Option A,B,C gets eliminated,

Option D,E remains

D uses like to give examples which is incorrect

So E

Other way we can also look,We can not use like to give examples, that leaves us Option B and E, Now E is parallel and exact meaning

(A) perhaps as well impairs the quality of such farm products like
(B) perhaps as well impairs the quality of such farm products as
(C) perhaps also impairs the quality of such farm products like
(D) may also impair the quality of such farm products like
(E) may also impair the quality of such products as

VeritasKarishma
GMATNinja
Bunuel
gmatt1476

I managed to eliminate and come down to b and e.
Why will we choose impair and not impairs considering air pollution is singular entity.

I managed to eliminate and come down to b and e.
Why will we choose impair and not impairs considering air pollution is singular entity

Anytime we have a helping verb, such as "may," it changes the form of the main verb. For example:

"Tim cooks dinner for his children every night, but only after they perform Les Miserables in its entirety."

Simple case here. "Tim" is singular, and the main verb, "cooks" is also singular. But watch what happens when we toss in a helping verb:

"Tim may cook dinner for his children..."

"Tim" is still singular, but because "cook" is paired with the helping verb "may" it takes a different form.

Same issue in (E): "Indoor air pollution may also impair."

Takeaway: when assessing subject-verb agreement, don't ignore helping verbs!

I hope that helps!
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Indoor air pollution can threaten the health of closely confined farm animals and the workers who tend them and perhaps as well impairs the quality of such farm products like eggs, poultry, and pork.

(A) perhaps as well impairs the quality of such farm products like
(B) perhaps as well impairs the quality of such farm products as
(C) perhaps also impairs the quality of such farm products like
(D) may also impair the quality of such farm products like
(E) may also impair the quality of such farm products as

Here in A and B 'perhaps as well' can't be parallel to 'can threaten' in the non - underlined part since meaning-wise 'perhaps' and 'as well' are opposite to each other. Also verb needs to be in base form due to the subjunctive nature of the sentence.

For others red highlighted text shows rejection of that option.
To mention examples 'such as' is required as is properly done in option E.
Correct answer E.

Question: Is 'perhaps also impair' in C correct(i opine that its correct)?
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Looking only at the parallelism in choice (C), we have, "Indoor air pollution (1) can threaten the health of closely confined farm animals and the workers who tend them and (2) perhaps also impairs the quality of..."

The singular verbs "can threaten" and "impairs" are parallel (we can ignore "perhaps also" while analyzing the parallelism). To see that more clearly, let's break up the list into two distinct pieces:

• (1) "Indoor air pollution can threaten the health of..."
• (2) "Indoor air pollution perhaps also impairs the quality of..."

These are both fine on their own, so the parallelism is okay in choice (C). But, again, choice (C) must be eliminated because of the "such... like".

I hope that helps!
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GMATNinja What is the correct logic for eliminating option B ?

The word "perhaps" indicates that we aren't sure whether indoor air pollution impairs the quality. Consider the following examples:

• "Smoking may increase the risk of lung cancer." - The word "may" indicates that we aren't sure about the claim that smoking increases the risk of lung cancer.
• "Smoking increases the risk of lung cancer." - This is a factual statement: smoking DOES increase the risk of lung cancer.
• "Smoking perhaps increases the risk of lung cancer." - The tense of the verb "increases" suggests that we are stating a fact (as in the previous example). But the word "perhaps" indicates that we aren't sure. So there's a discrepancy here.

The first option is a clearer way to express the uncertainty of the claim. Choice (E) is more clear than choice (B) for the same reason.

For more on the verbs in choices (B) and (E), check out this post.
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GMATNinja daagh VeritasKarishma generis egmat MartyTargetTestPrep

Even I have the same question. It will be great if any of the experts can kindly help on this.

How are may and perhaps different here? Why can't we use as well instead of also?

Hi pallavichsk,

Even if two words are similar in meaning, they may not be of the same type. May is a ("modal") verb here, whereas perhaps is an adverb.

After a modal, we expect to see the plain ("infinitive") form of a verb:
1. They may take...
2. She may take...

This does not happen with perhaps, which is an adverb. If we want to check the subject-verb agreement in this question, we must ignore the perhaps.
3. It perhaps impairs...
4. It perhaps impair...
5. They perhaps impairs...
6. They perhaps impair...
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