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555-605 Level|   Modifiers|   Parallelism|   Subject Verb Agreement|                  
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The peaks of a mountain range, acting like rocks in a streambed, produ 14 Apr 2020, 03:10
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KaranB1
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(A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are
This is one of those wordy GMAT sentences that probably has too many commas, so all of the answer choices basically “sound” the same. But in this case, there’s an easy elimination once you catch the subject-verb issue: after the semicolon, we have “the resulting flow pattern, [modifier blah blah], ARE known…”

That’s bad and wrong. (A) is out.

Quote:
(B) crests and troughs that remain stationary although they are formed by rapidly moving air, are
We can split some hairs over the differences between (A) and (B), but the subject-verb thing is a still a big, fat problem. (B) is out, too.

Quote:
(C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is
The subject-verb agreement is fine here, so that’s cool. We have perfect reasonable uses of the modifier “that” in both cases: “crests and troughs” are indeed the things “that remain stationary”, and “the air” is the thing “that forms them.” And “them” refers back to “crests and troughs.”

I don’t see any mechanical issues at all, so let’s keep (C).


Quote:
(D) stationary crests and troughs although the air that forms them is moving rapidly, are
Same subject-verb problem as in (A) and (B). I like free stuff, and this is basically free stuff. Thank you, GMAT, for taking mercy on us and letting us whittle this down to (C) and (E) in no time at all.

Quote:
(E) stationary crests and troughs although they are formed by rapidly moving air, is
Hm, there’s nothing explicitly WRONG with (E) in terms of grammar. The pronoun is OK (“they” refers to “stationary crests and troughs”), and so is the subject-verb agreement.

As we mentioned in our long-winded beginner’s guide to SC, once you eliminate everything you can based on DEFINITE grammar rules, then you’ll want to compare the remaining pairs side-by-side to see if there’s any meaning difference between the two:

    (C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is
    (E) stationary crests and troughs although they are formed by rapidly moving air

So what are the differences between these two? Well, (C) uses active voice (“the air that forms them is moving rapidly”), while (E) is passive (“they are formed by rapidly moving air”), and we could argue that the active voice is clearer and stronger in this particular case. (Though passive voice can be acceptable on the GMAT – but that’s a longer conversation for another day.)

More importantly, (C) does a better job of emphasizing the heart of the sentence. The thing that is (allegedly?) interesting about the crests and troughs isn’t simply that they are formed by rapidly moving air – and that’s basically what (E) says. The noteworthy thing is that the crests and troughs are stationary even though they are formed by rapidly moving air – and by putting the phrase “that remain stationary” right before “although the air that forms them is moving rapidly”, (C) emphasizes this fact much more clearly than (E) does.

Fun stuff. (C) is the best answer.

GMATNinja Sir, VeritasKarishma Ma'am

I have two doubts.

1. Why verb tense for answer C is not wrong. Should we not use simple present tense- Air that forms them moves rapidly.

2. Can we eliminate E for the fact "although" is contrasting noun with an action and not contrasting action with another action.

Please share your two cents.
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"Although" is a subordinating conjunction, hence it introduces a subordinate clause. This means it should have a main clause.

(C)
Crests and troughs remain stationary although the air that forms them is moving rapidly,
Main Clause

(E)
stationary crests and troughs although they are formed by rapidly moving air,
Noun, not a clause

In (C), both clauses are in present so it works. We may not be totally happy with it, but that's the thing about official questions - they teach us with what things we should be happy!
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The peaks of a mountain range, acting like rocks in a streambed, produ 20 Dec 2020, 11:38
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OG Solution:
The main challenge in this sentence is to observe the agreement of subject and verb (the resulting flow pattern... is known...) despite the distraction of a complex intervening structure containing several plural elements (with crests and troughs...). Choices A, B, and D can, therefore, be eliminated because they use an incorrect plural verb form, are. Choice E uses the correct verb form, is, but it incorrectly introduces a dependent adverbial although clause into a prepositional phrase (with crests ...). Choice D also makes this error. Such dependent clauses can only occur in the predicates of full clauses. C, the best choice, uses the correct verb form, is, and correctly puts the although clause inside the predicate of the relative clause (that... rapidly).

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The peaks of a mountain range, acting like rocks in a streambed, produ 22 Dec 2020, 21:40
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I clearly get why C is right but then i have a doubt
In the option which is :
crests and troughs that remain stationary although the air that forms them is moving rapidly, is

I think , "that clause is modifying only troughs and not crests"

Please correct me .
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The peaks of a mountain range, acting like rocks in a streambed, produ 22 Dec 2020, 23:30
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medhawi

I think , "that clause is modifying only troughs and not crests"
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Hi medhawi, there is considerable flexibility in terms of what that can modify.

For example, in the following sentence that is modifying devastation and enslavement.

For many revisionist historians, Christopher Columbus has come to personify the devastation and enslavement in the name of progress that have decimated the native peoples of the Western Hemisphere.

p.s. Our book EducationAisle Sentence Correction Nirvana discusses modifier issues of "that", their application and examples in significant detail. If you or someone is interested, PM me your email-id; I can mail the corresponding section.
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The peaks of a mountain range, acting like rocks in a streambed, produ 29 May 2021, 10:42
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The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, are known as "standing waves."

(A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are -> "the resulting flow pattern" is singular, so we nee singular verb, "are" is plural and Incorrect to use here.

(B) crests and troughs that remain stationary although they are formed by rapidly moving air, are -> Same as A.

(C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is -> No errors as such. we have clear contrast available too. Let's keep it.

(D) stationary crests and troughs although the air that forms them is moving rapidly, are -> Same as A.

(E) stationary crests and troughs although they are formed by rapidly moving air, is -> "stationary crests and troughs" and "they are formed by rapidly moving air..." are incorrect contrast. Incorrect.

So, I think C. :)
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The peaks of a mountain range, acting like rocks in a streambed, produ 29 May 2021, 22:32
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kinshuk97gupta
We won't have two correct answers, so always look for an error in the wrong ones, not just a preference, such as "this is shorter."

In this case, E is not just awkward, as some have suggested. It is grammatically wrong. When we have "although" in front of a clause, we need to contrast with another clause, either preceding or following. So if I say "although they are formed by rapidly moving air," I need to contrast with another clause, such as "they remain stationary." We can't say with noun, although clause, unless I am contrasting with some earlier action, such as "I argued with my brothers, although I knew they were right."
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The peaks of a mountain range, acting like rocks in a streambed, produ 30 May 2021, 03:14
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ERROR ANALYSIS -

1) 'are' doesn't agree in number

ANSWER CHOICE ANALYSIS -

A) 'are' doesn't agree in number
B) 'are' doesn't agree in number
C) CORRECT
D) 'are' doesn't agree in number
E) Grammatically correct but by meaning, the contrast is related to air flow pattern, but in this sentence the contrast of crest and trough has been highlighted
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The peaks of a mountain range, acting like rocks in a streambed, produ 30 May 2021, 18:42
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minalgambhir
E is definitely not grammatically correct (see my post above). Let's avoid reiterating that, since folks seem to be getting confused.
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The peaks of a mountain range, acting like rocks in a streambed, produ 29 Jun 2021, 22:11
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the 'that' modifies only troughs. But shouldn't we be modifying both crests and troughs? I thought 'that' always follows the touch rule
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The peaks of a mountain range, acting like rocks in a streambed, produ 30 Jun 2021, 00:39
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sehwag98
First, like almost everything in English grammar, the "touch rule" isn't an absolute rule. Second, we can (and often will) modify phrases that consists of more than one word, so in this case "that" is still touching the phrase "crests and troughs." The intended meaning is to modify that whole thing--crests and troughs--and there's no obstacle to interpreting it that way, so that's what we should do.
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The peaks of a mountain range, acting like rocks in a streambed, produ 23 Jul 2021, 09:36
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For option C
Can i ask how ‘that’ is valid for ‘troughs and crests’ ? I think that is used for singular nouns only but here we have a case of plural noun. Can someone please explain

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The peaks of a mountain range, acting like rocks in a streambed, produ 14 Aug 2021, 03:44
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Sks0106
For option C
Can i ask how ‘that’ is valid for ‘troughs and crests’ ? I think that is used for singular nouns only but here we have a case of plural noun. Can someone please explain

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HI! I don't think there is any rule that states that can only modify singular items. It can modify plural too, we just need to take care of subject verb agreement.
Example
1. I have cakes that are tasty.
2. I have a cake that is tasty.
Both are correct.
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The peaks of a mountain range, acting like rocks in a streambed, produ 14 Aug 2021, 07:58
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Sks0106
For option C
Can i ask how ‘that’ is valid for ‘troughs and crests’ ? I think that is used for singular nouns only but here we have a case of plural noun. Can someone please explain
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Hi Sks0106, the distinciton is:

i) When that is used as a relative pronoun (as is the case here), that can relate to both singular and plural nouns.

For example, both of the following are correct:

I have a car that is old.

I have cars that are old.

ii) When that is used as a demonstrative pronoun, that can refer only to singular nouns.

For example, following is correct:

Peter's book is older than that of Jack.

But, following is incorrect:

Peter's books are older than that of Jack.
- that is intended to refer to the plural noun books, but this is not allowed.

The correct sentence is:

Peter's books are older than those of Jack.

p.s. Our book EducationAisle Sentence Correction Nirvana discusses the avatars of “that”. Have attached the corresponding section of the book, for your reference.
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Avatars of that.pdf [245.5 KiB]
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The peaks of a mountain range, acting like rocks in a streambed, produ 03 Sep 2021, 00:56
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DmitryFarber
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We won't have two correct answers, so always look for an error in the wrong ones, not just a preference, such as "this is shorter."

In this case, E is not just awkward, as some have suggested. It is grammatically wrong. When we have "although" in front of a clause, we need to contrast with another clause, either preceding or following. So if I say "although they are formed by rapidly moving air," I need to contrast with another clause, such as "they remain stationary." We can't say with noun, although clause, unless I am contrasting with some earlier action, such as "I argued with my brothers, although I knew they were right."
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Hello! Can you comment more upon this explanation? Here how is crest and trough remain stationary a clause? A clause needs to have subject and verb. Maybe its a different type of clause. Can you elaborate more upon it? I understood X although Y needs to have clause on both sides. AndrewN IanStewart

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The peaks of a mountain range, acting like rocks in a streambed, produ 03 Sep 2021, 05:46
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pk6969

Here how is crest and trough remain stationary a clause? A clause needs to have subject and verb.
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"Crests and troughs" is the subject, and "remain" is a verb. If you want clarification of the rule that Dmitry was describing, you'll have to ask him about that, but he's right that there is a grammatical issue in answer E.
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The peaks of a mountain range, acting like rocks in a streambed, produ 03 Sep 2021, 05:52
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pk6969
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kinshuk97gupta
We won't have two correct answers, so always look for an error in the wrong ones, not just a preference, such as "this is shorter."

In this case, E is not just awkward, as some have suggested. It is grammatically wrong. When we have "although" in front of a clause, we need to contrast with another clause, either preceding or following. So if I say "although they are formed by rapidly moving air," I need to contrast with another clause, such as "they remain stationary." We can't say with noun, although clause, unless I am contrasting with some earlier action, such as "I argued with my brothers, although I knew they were right."

Hello! Can you comment more upon this explanation? Here how is crest and trough remain stationary a clause? A clause needs to have subject and verb. Maybe its a different type of clause. Can you elaborate more upon it? I understood X although Y needs to have clause on both sides. AndrewN IanStewart

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Hello, pk6969. I am not sure I understand the issue, other than that you may be having trouble parsing the clause in (C):

with crests and troughs that remain stationary—a prepositional phrase

crests and troughs—a plural noun element

that remain stationary—a relative clause that modifies the aforementioned crests and troughs

Compare to the corresponding element in (E):

with stationary crests and troughs—again, a prepositional phrase

stationary—an adjective that modifies the plural noun element that is about to follow

crests and troughs—exactly as above, a plural noun element

Thus, we can see that, ahead of the contrast marker although in both sentences, (C) incorporates a clause while (E) does not. Note that clause does not always mean independent clause. Perhaps that lies at the root of your misunderstanding.

I hope that helps. Thank you for thinking to ask.

- Andrew
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The peaks of a mountain range, acting like rocks in a streambed, produ 06 Sep 2021, 02:06
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kinshuk97gupta
We won't have two correct answers, so always look for an error in the wrong ones, not just a preference, such as "this is shorter."

In this case, E is not just awkward, as some have suggested. It is grammatically wrong. When we have "although" in front of a clause, we need to contrast with another clause, either preceding or following. So if I say "although they are formed by rapidly moving air," I need to contrast with another clause, such as "they remain stationary." We can't say with noun, although clause, unless I am contrasting with some earlier action, such as "I argued with my brothers, although I knew they were right."

Hello! Can you comment more upon this explanation? Here how is crest and trough remain stationary a clause? A clause needs to have subject and verb. Maybe its a different type of clause. Can you elaborate more upon it? I understood X although Y needs to have clause on both sides. AndrewN IanStewart

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Hello, pk6969. I am not sure I understand the issue, other than that you may be having trouble parsing the clause in (C):

with crests and troughs that remain stationary—a prepositional phrase

crests and troughs—a plural noun element

that remain stationary—a relative clause that modifies the aforementioned crests and troughs

Compare to the corresponding element in (E):

with stationary crests and troughs—again, a prepositional phrase

stationary—an adjective that modifies the plural noun element that is about to follow

crests and troughs—exactly as above, a plural noun element

Thus, we can see that, ahead of the contrast marker although in both sentences, (C) incorporates a clause while (E) does not. Note that clause does not always mean independent clause. Perhaps that lies at the root of your misunderstanding.

I hope that helps. Thank you for thinking to ask.

- Andrew
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Hi! Thanks for clearing it! Though I have one doubt. Wouldn't that make a dependent clause on one side and independent on the other? I saw post in which I read that for conjunctions, both sides should have same clause. Is that true?
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The peaks of a mountain range, acting like rocks in a streambed, produ 06 Sep 2021, 08:29
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Hi! Thanks for clearing it! Though I have one doubt. Wouldn't that make a dependent clause on one side and independent on the other? I saw post in which I read that for conjunctions, both sides should have same clause. Is that true?
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Hello again, pk6969. In a perfectly parallel world, sure, both sides of a parallel construct will be identical, but they do not have to match word for word to be considered parallel. If you are unsure about parallelism in an answer choice, then look for other more obvious issues while you place that consideration on hold. Parallelism should not be foremost on your list of considerations anyway.

- Andrew
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The peaks of a mountain range, acting like rocks in a streambed, produ 19 Nov 2021, 01:09
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Hi Everyone. I have a doubt here. How can "them" in Option C refer to two different antecedents and be perfectly okay to be the correct answer? Is it okay to have same pronouns to have two different (but logical) antecedents? (Unlike what explicitly cited on Manhattan GMAT guide) Or is it okay because both the ICs are separated here by a semi-colon. I genuinely confused. Thanks.
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The peaks of a mountain range, acting like rocks in a streambed, produ 19 Nov 2021, 03:40
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wps002
Hi Everyone. I have a doubt here. How can "them" in Option C refer to two different antecedents and be perfectly okay to be the correct answer? Is it okay to have same pronouns to have two different (but logical) antecedents? (Unlike what explicitly cited on Manhattan GMAT guide) Or is it okay because both the ICs are separated here by a semi-colon. I genuinely confused. Thanks.
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Hello wps002,

We hope this finds you well.

Having gone through the question and your query, we believe we can resolve your doubt.

Here, "them" does not refer to "crests" and "troughs" independently, rather, "them" refers to the combined noun phrase "crests and troughs"; thus, "them" has only one antecedent. Remember, two nouns joined by "and" form a single, plural noun phrase.

To understand the concept of "And" versus Other Conjunctions on GMAT, you may want to watch the following video (~1 minute):



All the best!
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