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 what are now temperate areas

(A) in which great ice sheets had existed in what are now temperate areas
(B) in which great ice sheets existed in what are now temperate areas
(C) when great ice sheets existed where there were areas now temperate
(D) when great ice sheets had existed in current temperate areas
(E) when great ice sheets existed in areas now that are temperate


This qs is from GMAT Prep test. I don't understand why the OA is B and not A?

MGMAT says the following is correct in its SC Guide:

The teacher THOUGHT that Jimmy HAD CHEATED on the exam.

Isn't this the same idea?

... studies LED him to propose that ... HAD MELTED

Hey acethegmat, that's a really good question. But it's not quite the right question. In the original, (A) reads "in which great ice sheets had existed in now currently temperate areas."

The giveaway there is "now currently," which is redundant.

I don't think that there's an actual GMAT question with an answer that is wrong solely because it uses simple past when past perfect is justified.

Notice justified. The Strategy Guide examples you cite show when past perfect is appropriate, but it past perfect isn't required in every such tense.

Dear instructors,

I have a question about the relative clause in this sentense.

"the concept of an age in which..."

I think the "in which" here refers to "the age", rather than "the concept". But I remember that in "A of B+which/that clause" structure, the "which/that" should modify A, not B. Am i wrong?

Could you clarify that? Thanks very much!

yes -- this is clear from the context. i.e., the mentioned events happened within a timeframe, not within a concept.


from your own conclusion above, you can figure out that, yes, you are wrong. (:
i'm not being sarcastic here -- i'm actually trying to point out that, since correct answers are correct, you can use the content of the correct answers to answer a lot of these questions yourself.

in general, given a construction NOUN1 + PREPOSITION + NOUN2, a following modifier can usually refer to either NOUN1 or NOUN2.
in general, you're going to need to use the meaning of the sentence to figure out which of those two nouns is the intended referent. in fact, that may be a partial diagnosis of the problem right there -- you may be looking for a purely grammatical rule here, when in fact you have to use context as well. (an exceedingly common problem in SC)

For the above question, could someone please clarify whether it's grammatically correct to use "in which" and "when" to refer to age. Can we use anyone of " in which"/ "when" to refer to age without any grammatical error?

i believe that either is fine.

(A) in which great ice sheets had existed in what are now temperate areas
(B) in which great ice sheets existed in what are now temperate areas

The only difference between option A & B is 'existed' & 'had existed'. Could you please tell why the OA is B and not A.

the correct sentence in option 'A' is
(A) in which great ice sheets had existed in now currently* temperate areas

now and currently are redundant here.

* - It was a typo by the original poster

Secondly, if the sentence makes sense in both past and past perfect tense, we should usually go with the past tense rather than the past perfect.

thanks for that correction. to the other poster, please double-check the answer choices that you are posting.

a couple of things about verb tenses:

* first of all, studying verb tenses should be a low priority. verb tenses are VERY rarely tested alone -- i.e., they are usually tested in tandem with other errors, which can also be used to eliminate the choices -- so they aren't as important as more major topics, such as parallelism and pronouns.
there's also the fact that verb tenses are by far the most difficult aspect of any language for non-native speakers to learn. (this is not a fact about the english language in particular; this fact is true about any language in the whole world.) so, if you are not a native speaker of english, you will almost certainly derive a greater return on investment by putting your study time into other aspects of these sentences. this is doubly true because, as i said above, almost no problems require the use of verb tenses to get the right answer.

* regarding the perfect tenses (present perfect and past perfect):
the point of the perfect tenses is to stress one of two things:
* the completion of some action prior to the timeframe of the sentence, or
* the persistence of some state up to the timeframe of the sentence.
for instance, if i write by the time i arrived, all of the food had been eaten, i'm emphasizing the completion of this act -- it's all done; the food is all gone. if i write when i took him to the doctor, johnnie had already been sick for two weeks, the emphasis is not on the idea that johnnie was sick at the time of the sentence; the emphasis is on the fact that he had been sick for the previous two weeks -- a persistent condition.
this is the reason why “an age in which great ice sheets had existed” doesn't really make sense here. the emphasis of the sentence is on the fact that the ice sheets ACTUALLY EXISTED during this time. the sentence is not meant to emphasize the persistence of the ice sheets before that age, nor is it meant to suggest that the existence of the ice sheets was a completed action. therefore, the regular past tense is better.

again, i doubt that any of this will ever be required to solve one of these problems, but there you go.

Ron, I still don't quite understand the usage of Past Simple in (B). Louis Agassiz proposed a theory in the past. This theory was about ice sheets that had existed before and from the past perfect tense in the original sentence you can conclude that those ice sheets no longer existed when he proposed his theory. Now, changing the tense to past simple it's not clear (at least not to me) whether the ice sheets existed at the time when he proposed his theory.

I do understand that there is a problem with "in now currently". But I want to understand this past perfect to past simple shift.

Thanks a lot.

that long paragraph you quoted is my best attempt at explanation here. if you still don't understand, the best decision would be to let this particular difference go.

read, again, the first lines of my quoted response -- verb tenses are a very low priority.
* if there is a split in verb tenses, that split will almost always be accompanied by other issues.
* if a split in verb tenses does appear alone, it will be a distinction much more obvious than past versus past perfect.



i can give a couple more examples:

ron told me about the questionable diet that he ate as a child.
--> random past event with timeframe given
--> no direct relevance to the situation at hand
--> no emphasis on “completed action”

james developed diabetes as an adult because of the questionable diet that he [i]had eaten as a child.[/i]
--> the sentence emphasizes the direct impact of eating the diet; that sort of direct impact justifies the past perfect.

john told me about the meal that he had just eaten.
--> the sentence emphasizes “completed action”, so the past perfect is used.

the sentence at hand is a lot more like the first of these examples than like the other two.

Pls explain the usage of 'in which' and 'when'
can we eleminate the options here on the basis of 'in which/when' split??
If usage of both 'in which and when' is right and if option 'E' is modified to - 'when great ice sheets existed in areas that are now temperate', then between 'B' and the modified 'E', which is a better option?

nope. in this case, both are fine.



if you made those changes at the end of choice (e), then it would become another correct version of the sentence. in that case, each of (b) and (e) would be just as good as the other.