Now, if you were to get an explanation from the Official Guide book itself, notice the difference in explanation depth and attack strategy compared to GMATPill’s explanation above. According to most students, the official guide explanations don’t really give them a good enough thought process to attack the question. And sometimes, it’s just difficult to follow.

A) Not only did the systematic clearing of forests in the United States create farmland (especially in the Northeast) and gave consumers relatively inexpensive houses and furniture, but it also
B) Not only did the systematic clearing of forests in the United States create farmland (especially in the Northeast), which gave consumers relatively inexpensive houses and furniture, but also
C) The systematic clearing of forests in the United States, creating farmland (especially in the Northeast) and giving consumers relatively inexpensive houses and furniture, but also
D) The systematic clearing of forests in the United States created farmland (especially in the Northeast) and gave consumers relatively inexpensive houses and furniture, but it also
E) The systematic clearing of forests in the United States not only created farmland (especially in the Northeast), giving consumers relatively inexpensive houses and furniture, but it

What is this GMAT question testing?

This question tests the infamous “Not only….but also” construction that the GMAT guys LOVE to use.

You’re also expected to be able to identify inconsistencies in verb tenses in the context of long sentences.

For example, notice the variations in verb tenses in the following two examples:
“Not only did it create….but it also caused”
“Not only does it create…but it also causes”

The first one uses past tense verbs “did” and “caused.”
the second one uses present tense verbs “does” and “causes.”

But GMAT questions always try to complicate things.

How do you know when to use
“Not only ABC, but also XYZ”
versus
“Not only ABC, but it also XYZ” ?

Well, the above is a perfect example testing you on this so check out the video above!

And note that in answer B, it is not wrong because of the present/past tense. Past tense is actually OK here because the phrase “Not only DID….but it also DID THIS” implies a past tense to be used in the latter half of the sentence. So the past/present tense is not the issue here.

For B, the issue is that “but also” should be “but it also” because the structure of this sentence is “Not only did it do this….but it also did this”. If we leave out the “IT”, it will somehow be a continuation of the phrase right before the comma…and in this case that wouldn’t make sense.

The key is to figure out what the GMAT guys are testing you on and to move your eyeballs to the critical keywords ASAP so you can do the necessary analysis and choose the correct answer.