If you’ve spent any amount of time studying for GMAT Sentence Corrections, you’re probably familiar with the concept of parallel structure — that is, items in a list or on either sides of a conjunction must be presented in the same format.
Many of these questions are relatively straightforward: you simply ensure that the various items in a list match (verb, verb, verb; noun, noun, noun, etc.). But in addition to those types of questions, the GMAT also like to test subtler forms of parallel structure, one of which involves the word that.
For example, let’s start with this sentence:
The globe’s southernmost continent hasn’t always been ice-bound: the discovery of fossil ferns, pines, and ginkgoes from the Cretaceous Era indicates that Antarctica was once a warm place, and many plant and animal species living quite comfortably close to the South Pole.
If you recognize that the gerund living creates a fragment, then you can probably determine that this version of the sentence isn’t correct.
Or, if you consider things from the standpoint of general parallel structure, you can probably see that there’s a problem: the clause before the underlined section contains two conjugated verbs (indicates, was) whereas the underlined portion contains the gerund living.
That’s important information, and it at least tells you that the original version is wrong. It also gives you some idea of what information the right answer will contain. It does not, however, give you one specific, concrete piece of information that will allow you recognize the correct answer immediately and with almost 100% certainty.
That said, we’re going take another look at the sentence:
The globe’s southernmost continent hasn’t always been ice-bound: the discovery of fossil ferns, pines, and ginkgoes from the Cretaceous Era indicates that Antarctica was once a warm place, and many plant and animal species living quite comfortably close to the South Pole.
If you already have an inkling that the error in this sentence has something to do with parallel structure, the appearance of the word that in the non-underlined portion provides an important clue, namely that the correct answer will also include the word that.
Now, look at the answers — can you spot it?
(A) and many plant and animal species living quite comfortably close
(B) and many plant and animal species would live quite comfortably close
(C) and that many plant and animal species lived quite comfortably close
(D) many plant and animal species had lived quite comfortably in close proximity
(E) with many plant and animals species lived quite comfortably and in close proximity
The only option to include that is (C). And in fact, that is the answer.
If we “strip” the relevant portion of the sentence down to its essential structure, we can see how it works: the discovery of fossils ferns, etc. from the Cretaceous Era indicates that Antarctica was…and that many plant and animal species lived…
To reiterate: the GMAT really, really likes this construction. By my count, it appears five times in correct answers in the 2017 Official Guide (questions #724, 737, 756, 793, and 795). Learning to recognize it quickly is a shortcut that’s absolutely worth mastering.