Hey Nithin,

Great question - while C is parallel, it misses another important part of the sentence. When you begin a sentence with "Although" or another word that signals that a transition is coming (like "because"), it must be followed by an independent clause - you need a subject and a verb to follow the lead-in of "although" or "because".

For example, I couldn't say that:

Although it was raining last night and I went for a run.

Because there's no second half to that sentence. I would say:

Although it was raining last night, I went for a run.

We need "I" as a new subject to follow the clause "Although..." You can think of this as a cause-and-effect relationship: "Although X is true, Y is also true."


In this sentence, C doesn't provide a second half to that relationship, so although it's parallel in verb tense, it's still incorrect. We need a choice like A which is not only parallel, but also introduces "they" as the subject of a new clause to complete the "although X is true, Y is also true" situation.
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(A) acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate

CORRECT: This answer choice conveys the intended meaning in a clear and idiomatically correct fashion;
Adverbial modifier -- acting as a global thermostat -- correctly modifies the clause about the ice particles' reflection and absorption of solar radiation, describing the results of those phenomena
The main clause ‘they also accelerate’ starts in the correct place, and, as expected from subordinating conjunction ‘although’, stands in conceptual opposition to the subordinate clause that begins the sentence; The subordinating conjunction ‘although’ is used to introduce a contrast BETWEEN the clause introduced by ‘although’ (subordinate clause) AND the clause following the comma (main clause) - ‘Although [subordinate clause], [main clause]’;



(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating

Meaning: the placement of the preposition ‘from’ in the construction ‘keeping Earth EITHER from burning up OR freezing over’ doesn’t make sense in the given context, as it implies that preposition ‘from’ applies only to the first part of the construction; In other words, ‘Ice particles act as global thermostat and thus EITHER keep Earth from burning up OR keep Earth freezing over’; obviously, the preposition ‘from’ has to be placed before the ‘EITHER..OR’ construction, because ‘keeping Earth freezing over’ doesn’t logically qualify as a ‘benefit’: ‘… thus keeping Earth from EITHER burning up OR freezing over…’
Construction: subordinating conjunction ‘Although’ is used to introduce a contrast BETWEEN the clause introduced by ‘although’ (subordinate clause) AND the clause following the comma (main clause) - ‘Although [subordinate clause], [main clause]’. This answer choice is a sentence fragment, as it lacks the main clause and consists of one subordinate clause followed by modifiers - ‘Although [subordinate clause], [modifier], [modifier], [main clause –missing]’; furthermore, since the main clause is missing, the implication is that the modifier ‘while also accelerating the destruction of the ozone layer by reacting with chlorofluorocarbons’ is further describing the benefits of ice particles, whereas, clearly, there is nothing beneficial in the destruction of ozone layer;


(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating

Meaning/Construction: This answer choice makes no grammatical sense; it seems to present a list of benefits, but with complete disregard to parallelism and punctuation: ‘reflect and absorb..., act as X, and thus..., while also accelerating ....’; furthermore, this answer choice is a sentence fragment, as it lacks the main clause and consists of one subordinate clause followed by a long modifier - ‘Although [subordinate clause], [modifier], [main clause –missing]’; furthermore, since the main clause is missing, the implication is that the modifier ‘while also accelerating the destruction of the ozone layer by reacting with chlorofluorocarbons’ is further describing the benefits of ice particles, whereas, clearly, there is nothing beneficial in the destruction of ozone layer;


(D) they act as a global thermostat that thus keeps the Earth either from burning up or freezing over even though it also accelerates

Meaning: the subordinating conjunction ‘Although’ is used to introduce a contrast BETWEEN the clause introduced by ‘although’ (subordinate clause) AND the clause following the comma (main clause) - ‘Although [subordinate clause], [main clause]’; Clearly, there is no apparent contrast between the subordinate clause (Although ice particles benefit Earth in that they reflect and absorb solar radiation) and the main clause (they act as a global thermostat)’; on the contrary, the ‘global thermostat’ idea flows smoothly from the ice particles' reflection and absorption of solar radiation.
Unidiomatic: construction ‘thermostat that THUS keeps’ is unidiomatic, the ‘thus’ is completely out of place and unnecessary;
Meaning: the placement of the preposition ‘from’ in the construction ‘keeps the Earth EITHER from burning up OR freezing over’ doesn’t make sense in the given context, as it implies that preposition ‘from’ applies only to the first part of the construction; In other words, ‘Ice particles act as global thermostat and thus EITHER keep Earth from burning up OR keep Earth freezing over’; obviously, the preposition ‘from’ has to be placed before the ‘EITHER..OR’ construction, because ‘keeping Earth freezing over’ doesn’t logically qualify as a ‘benefit’;
Awkward: aside from using a contrasting conjunction ‘although’ without apparent contrast, this answer choice adds another contrasting conjunction ‘even though’, thereby creating an even more awkward sentence;


(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate

Meaning: the subordinating conjunction ‘Although’ is used to introduce a contrast BETWEEN the clause introduced by ‘although’ (subordinate clause) AND the clause following the comma (main clause) - ‘Although [subordinate clause], [main clause]’; Clearly, there is no apparent contrast between the subordinate clause (Although ice particles benefit Earth in that they reflect and absorb solar radiation) and the main clause (they act as a global thermostat)’; on the contrary, the ‘global thermostat’ idea flows smoothly from the ice particles' reflection and absorption of solar radiation.
Meaning: construction ‘they (ice particles) act as thermostat TO THUS keep Earth…’ nonsensically implies that ‘ice particles intentionally act as thermostat to protect the earth from extreme temperatures’, obviously ‘ice particles are inanimate objects that don’t have free will, not to mention intentions’
Awkward: aside from using a contrasting conjunction ‘although’ without apparent contrast, this answer choice adds another contrasting conjunction ‘but’, thereby creating an even more awkward sentence;

To me A is a perfectly sensible choice.


#1. Orange part is a dependent clause
#2.Green part is modifying the subject of the main clause - i.e. "they"
#3. You cannot have "a" before "global thermostat", since "global thermostat" is referring to "they" ("they itself is referring to "ice particles")

can anybody explain why not c...its parallel

A) acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate
(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
(D) they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates
(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate

B

Ohhh god I missed the beginning.

Question - shouldn't the idiom be either from X or Y ? In A this is from either X or Y.
Are both correct ?

Hi Amma,

Great point -and this is why I always advocate to think about idioms LAST, because:

1) Very seldom does a GMAT question rely solely on the idiom...there's almost always a more systematic flaw in 4 of the answers.

2) We're just not that good at idioms...there are too many to know and too many exceptions to the rule. And why would a top business school be impressed that you memorized 20% more idioms than I did? It's applying systematic knowledge that should impress them.

As to your question specifically, I think you can break that one down to parallelism, though:

Either _______________ or _________________

Dictates that if the "from" comes after "either", you'd need it in the second half, after "or", as well:

Either from X or from Y

OR you could put the "from" first so that it corresponds to both halves:

From either X or Y
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Why is B , C, E out ?? Is B and C out for the use of while? and E out for the use of but???

Hi @siddhans,

Use of although makes a clause a dependent clause that needs to be supported with an independent clause to communicate a complete idea. For example: Although this house is small, it can accommodate a lot of people. Notice that "Although this house is small," does not communicate a complete idea. It needs the help of an IC to do so.

Choice B is made up of two DCs. This sentence structure is not correct. After the "although" DC, we need an IC to communicate a complete idea. Also this choice violates parallelism. What follows "either" is "from burning up" and what follows "or" is "freezing over". We need "from" after "or" also to make both the entities parallel.

Choice C has the same sentence structure problem with the use of "while".

Choice E again has a faulty sentence structure because of the presence of "but" after comma.

Hope this helps.
Shraddha


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Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

(D) they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates

Gurus,
I have a question is the below construction correct. I want to know whether the construction of above sentence correct.(i know there are few errors in this sentence but is the construction correct)


Although DC, IC, even though DC.

Hi,

I received a PM to respond to this one.

Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

There are four clauses in this sentence with choice D:

Cl. 1: Although ice particles in the upper atmosphere benefit Earth (DC)

Cl. 2: in that they reflect and absorb solar radiation, (DC)

Cl. 3: they act as a global thermostat that thus keeps Earth either from burning up or freezing over (IC)

Cl. 4: even though it also accelerates the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's). (DC)

The highlighted words in the first two clauses and the last clause make them dependent clauses. The third clause is an IC. This construction is correct. The first two DCs are connected correctly. The DCs and the IC are correctly connected by comma. Then the last DC is connected by the previous IC by a comma.

Hope this helps.
Thanks.
Shraddha
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Because "Although" in the non-underlined part has contrast meaning, we do NOT need to add "while/but/even though..." in the second part. Thus, only A is correct.

Grammar:
Although X, Y <== There is NO "but, while,...." before Y.

Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

(A) acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate
CORRECT. The blue part is Verb-ING modifier.

(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
WRONG. [ Although X, while Y ] is wrong structure.

(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
WRONG "while" is redundant. "act....and keep" should be verb-ing modifier.

(D) they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates
WRONG. "even though" is redundant. "it" does not match "particles"

(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate
WRONG. "but" is redundant.

Regards,

Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation,............................. , they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

30 seconds approach, even less .

I do not even rely on idioms or else........only in case of blurry situations.

Good job
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Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chlorofluorocarbons (CFC's).

(A) acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate :
Correct : modifier “acting” correctly modifies the verb benefit
Construction of “Although ….., they also ….” Is correct

(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
Incorrect : parallelism error “either from burning up or (from) freezing” – from is required before “freezing” to correct this error
Construction of “Although …., while …” is awkward and incorrect

(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
Incorrect : Construction of “Although …., while …” is awkward and incorrect
Verb “act” is now associated with ice particles and is highlighting another action of the ice particles rather than providing information about how they benefit earth.

(D) they act as a global thermostat that thus keeps Earth either from burning up or freezing over, even though it also accelerates
Incorrect : Construction “although ….even though” redundant…
Pronoun error : “it also accelerates” – is singular ..we are talking about ice particles (plural)

(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate
Incorrect : “they act …to thus keep earth ….” Change in meaning
They act that way and thus it helps earth…they do NOT in particular act that way IN ORDER to help earth…
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Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chloroflurocarbons (CFC's).

(A) acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate

(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating Wrong usage missing noun in Independent Clause

(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating Wrong usage missing noun in Independent Clause

(D) they act as a global thermostat that thus keeps the Earth either from burning up or freezing over, even though it also acceleratesAlthough shows contrast even though is not needed

(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate Although shows contrast but is not needed

This question is a classic example of why one should know the fundamentals of grammar such as the patterns of sentences including simple, complex, and compound and their derivatives.

A significant 80% of the errors of fragments, run-ons, subjunctives, conditionals, modifications, etc are built on such sentence patterns without knowing which it is pointless to attempt GMAT.
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(A) acting as a global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate - Correct

(B) acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating - Wrong: 1) Parallelism 2) Structure

(C) act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating - Wrong: 1) Meaning

(D) they act as a global thermostat that thus keeps the Earth either from burning up or freezing over, even though it also accelerates - Wrong: 1) SV 2) Parallelism 3) Pronoun

(E) they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate - Wrong: 1) Meaning

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