According to scientists at the University of Alaska

[alohabrian]

According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees.


(A) the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees

(B) the surface temperature in Alaska, Siberia, and northwestern Canada has increased over the last thirty years by about five degrees

(C) there was an increase in the last thirty years by about five degrees in Alaska, Siberia, and northwestern Canada

(D) it had increased in Alaska, Siberia, and northwestern Canada by about five degrees over the previous thirty years

(E) it has increased in Alaska, Siberia, and northwestern Canada over the previous thirty years by about five degrees

Key : B

Dears, I cannot make a choice between A, B and E.
I prefer choice E; however, it proves incorrect.
Is the usage of "it" in choice E improper?

[alohabrian]

I am wondering that whether the "it" here can only be intrepreted as "the surface temperature of the globe".

Any taker ?

[JonathanSchneider]

I'm not a huge fan of the "it" here, but that's not the biggest of your worries. The bigger problem is the word "previous." This suggests the time period BEFORE the last century; however, this conflicts with the word "while" (meaning at the same time as) earlier in the sentence. The word "last" is more appropriate. A subtle difference, but an important one : )

[srihariom]

Hi Jonathon,
Can you please let me know if my understanding is correct.

Isn't choice a suggesting that the temperatue has increased every year for past 30 years when using "in the previous thirty years"


Whereas choice B properly suggests the temperature rose over a period of time.

Choice E has a pronoun ambiguity.

[jnelson0612]

Hi Jonathon,
Can you please let me know if my understanding is correct.

Isn't choice a suggesting that the temperatue has increased every year for past 30 years when using "in the previous thirty years"


Whereas choice B properly suggests the temperature rose over a period of time.

Choice E has a pronoun ambiguity.

I really don't read choice A that way. Because it uses a present perfect verb, I think A says that the increase began thirty years ago and over that thirty year period it has increased a total of five degrees. I don't think we can infer that there was some increase each year.

[benjamindian]

Is A wrong because we need to use "over" to make it parallel to "over the last century" or because we can't use "in the previous xx years" in present perfect tense? Thanks.

[RonPurewal]

Because the two parts express similar facts, they should be expressed as similarly as possible. (This isn't grammatical parallelism, strictly speaking, but the idea is the same.)

The first part uses "over". So, the second part"”which uses exactly the same sort of time construction"”should use "over", too.

("In" doesn't really make sense. It just notes that something has happened at some point during that period, rather than over the course of the entire period. But this is too subtle"”and favors native speakers too much"”to be the kind of thing that GMAC would test.)

[thanghnvn]

[quote="alohabrian"]According to scientists at the University of Alaska, while the surface temperature of the globe has risen over the last century by about one degree Fahrenheit, //the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees.//


(A) the surface temperature in Alaska, Siberia, and northwestern Canada has increased in the previous thirty years by about five degrees

(B) the surface temperature in Alaska, Siberia, and northwestern Canada has increased over the last thirty years by about five degrees

(C) there was an increase in the last thirty years by about five degrees in Alaska, Siberia, and northwestern Canada

(D) it had increased in Alaska, Siberia, and northwestern Canada by about five degrees over the previous thirty years

(E) it has increased in Alaska, Siberia, and northwestern Canada over the previous thirty years by about five degrees

Key : B

"it" in d and e is wrong because "it" refers to the whole " surface temperature of globe". this reference make ilogic sense.
"had increased" in D is wrong. the only usage of had done is to show that the action is finished before a past time/action. no other usage. this is a basic grammar problem. read a grammar book.

"in" in a is wrong. gmat test preposition refering to time heavily. read a grammar book for this point. "in " is used for future or in some time idioms such as "in summer, in 1980 vvvv. "in" is never used for a period of time.

in c, "there are increase" . what increase? it is not clear.

b is left.

[RonPurewal]

thanghnvn, do you have a question?