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Source: Official Guide for the GMAT 13th Ed. Sentence Correction; #72 Official Guide for the GMAT 2015 14th Ed. Sentence Correction; #72


His studies of ice-polished rocks in his

His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age (in which great ice sheets had existed in now currently temperate areas).

2 Explanations


Meera k

existence of rocks didn't happen before any other event so we need past tense only. A and D are incorrect for using the past perfect tense. Also A has redundancy with words now and currently. In E, that needs to refer areas but incorrectly seems to refer to word now. active voice is preferred to passive form of construction, thereby eliminating C and hence B is the correct choice.

Oct 15, 2016 • Comment

Sam Kinsman

Hi Meera,

Yes, you are right! Just note that the sentence does describe have actions that occur in different points in the past - but since we are not directly comparing two past actions, we don't need the past perfect. Also keep in mind that C is indirect, wordy, and sounds awkward in general! :)

Oct 17, 2016 • Reply


Gravatar Mike McGarry, Magoosh Tutor

May 22, 2013 • Comment

Hui Zhang

In B, why does it use "what", instead of "where"?

Jan 11, 2018 • Reply

David Recine

"What" is better than "where" for reasons related to style and awkwardness, rather than because of a specific grammar rule.

Basically, you don't want to use an unnecessary amount of words or create needless grammatical complexity. With "what" we have a pronoun that starts a new clause. This can be the subject of the clause and lead straight to a verb (as in "what are"). But if you use "where," in this context, the word "where" acts as a conjunction that precedes a new clause. So you then need to add a noun or pronoun and verb after "where," as in the very awkward "where there were," or something even more awkward, such as "where temperate areas now are."

Jan 15, 2018 • Reply

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