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by ankur.agrawal » Thu May 05, 2011 9:57 pm
Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

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by HSPA » Thu May 05, 2011 10:09 pm
CO levels = plural = 'it' = wrong
enough of increased percentage = awkward
second it has no proper antecedent

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.
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by AIM GMAT » Thu May 05, 2011 10:55 pm
Good question Ankur , this kind of questions usually do trap non natives ;) .

I could come down with two options C and E , but chose the wrong one :(

When i read the two options , really couldn't fine the meaning diffrence . I am not sure about What has begun to trap the heat radiating ? CO or CO levels .

I get the same answer in both the options , guys kindly provide some inputs if you get to know how to solve this discrepancy ?
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by HSPA » Thu May 05, 2011 11:42 pm
Yes I am sorry B is wrong... levels cannot trap heat...

IMO C
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by bubbliiiiiiii » Thu May 05, 2011 11:55 pm
ankur.agrawal wrote:Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

grew and increased are redundant.
, and - a seperator of IC, the second part of and has no subject.

Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.
Contender.
The only thing that is stopping me from choosing this as answer is the referrant of they which is carbon monoxide levels. Since, logically CO levels cannot trap heat. I am confused.

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

This gives me an idea that levels have purposely increased to trap heat radiation whereas due to the increase level the heat is trapped. Thus NO.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Same as C.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Contender.
Cause is increase and effect is trapping.
COMMA + verbing -> modifies preceeding noun or noun phrase 'trapping heat radiating from the Earth'.

Confused between B and E.

From HSPA, if B is not the answer, then IMO E.

Can anyone please elaborate on why not B as I feel that even in E the levels are trapping the heat as that in B.
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by AIM GMAT » Fri May 06, 2011 12:24 am
Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

The above option B , is wrong because of some awkward wordings and it states that the levels are causing the rise in temperature .

I too went for E , but experts say that the meaning inferrred from E is also wrong , the same issue that levels are not increasing the temp but CO .

I am not clear with the diffrence in Option C and E .Lets see what other members have to say on this .
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by ankur.agrawal » Fri May 06, 2011 1:45 am
AIM GMAT wrote:Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

The above option B , is wrong because of some awkward wordings and it states that the levels are causing the rise in temperature .

I too went for E , but experts say that the meaning inferrred from E is also wrong , the same issue that levels are not increasing the temp but CO .

I am not clear with the diffrence in Option C and E .Lets see what other members have to say on this .

MGMAT Explanation rejects E by saying:

"This choice alters the position of "during the twentieth century", thereby changing the meaning of the sentence. In this choice "during the twentieth century" modifies the carbon monoxide levels instead of describing when those levels "increased." This distorts the meaning by leaving open the possibility that carbon monoxide levels "increased enough" during some other time period (e.g., the 21st century)."

I dont see this difference. Can someone explain this. :)

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by GMATGuruNY » Fri May 06, 2011 3:31 am
ankur.agrawal wrote:Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.
In A, it (singular) doesn't agree with levels (plural). Eliiminate A.

In B, enough....that they began is unidiomatic. Also, enough of a percentage feels redundant. A better wording might be a sufficiently high percentage. Eliminate B.

In D, which incorrectly refers to Earth. Eliminate D.

In E, it is unclear whether during the twentieth century is an adjective modifying the atmosphere or an adverb modifying increased. It must be clear what a modifier is modifying. Eliminate E.

The correct answer is C.
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by 7777 » Fri Sep 07, 2012 8:16 pm
GMATGuruNY wrote:
ankur.agrawal wrote:Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.
In A, it (singular) doesn't agree with levels (plural). Eliiminate A.

In B, enough....that they began is unidiomatic. Also, enough of a percentage feels redundant. A better wording might be a sufficiently high percentage. Eliminate B.

In D, which incorrectly refers to Earth. Eliminate D.

In E, it is unclear whether during the twentieth century is an adjective modifying the atmosphere or an adverb modifying increased. It must be clear what a modifier is modifying. Eliminate E.

The correct answer is C.
is the use of they in 2nd option correct here?
i think levels didnt trap heat but CO did.

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by Mission2012 » Sat Sep 08, 2012 10:05 am
GMATGuruNY wrote:
ankur.agrawal wrote:Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.
In A, it (singular) doesn't agree with levels (plural). Eliiminate A.

In B, enough....that they began is unidiomatic. Also, enough of a percentage feels redundant. A better wording might be a sufficiently high percentage. Eliminate B.

In D, which incorrectly refers to Earth. Eliminate D.

In E, it is unclear whether during the twentieth century is an adjective modifying the atmosphere or an adverb modifying increased. It must be clear what a modifier is modifying. Eliminate E.

The correct answer is C.
Hi GMATGuruNY,

Need help.

Is there any thumb rule to spot such errors.
At first glace it appears to be a simple adjective modifying noun clause - "Levels of carbon monoxide in the atmosphere"
I could spot this error only when you pointed out.

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by GMATGuruNY » Sun Sep 09, 2012 3:19 am
I received a PM requesting that I explain the following points.

A: CARBON MONOXIDE levels in the atmosphere grew by enough of an increased percentage during the twentieth century that IT began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.
Here, carbon monoxide serves as an ADJECTIVE modifying levels.
What type of levels?
CARBON MONOXIDE levels.
It cannot serve to refer back to carbon monoxide; a PRONOUN cannot stand in for an ADJECTIVE.

B: Carbon monoxide LEVELS in the atmosphere increased by enough of a percentage during the twentieth century that THEY began to trap heat radiating from the Earth, causing the average surface temperature to rise.
Here, they refers to levels, implying that the LEVELS -- of their own volition -- BEGAN to trap heat.
Not the intended meaning: the levels on their own did not take action.

C: Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.
In the OA, sufficiently during the twentieth century to begin trapping heat serves as an ADVERB modifying increased.
HOW did the levels increase?
They increased sufficiently during the twentieth century to begin trapping heat.
This is the intended meaning.
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