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Source: Official Guide for the GMAT 13th Ed. Sentence Correction; #86 Official Guide for the GMAT 2015 14th Ed. Sentence Correction; #86


In 2000, a mere two dozen products

In 2000, a mere two dozen products accounted for half the increase in spending on prescription drugs, a phenomenon that is explained not just because of more expensive drugs but by the fact that doctors are writing many more prescriptions for higher-cost drugs.

3 Explanations


Adam Gay

Hi Magoosh,

I am a little confused why a comma is sufficient to separate the 2 clauses. Can "a phenomenon.....higher-cost drugs" stand alone as an independent clause?


Feb 26, 2016 • Comment

Cydney Seigerman, Magoosh Tutor

Hi Adam :)

Good question! In this case, "a phenomenon ... higher-cost drugs" is not an independent clause. There is no main verb in this clause. Rather, the clause modifies the observation described in the first part of the sentence, which we can determine thanks to the presence of "that": the observation is "a phenomenon that is explained..." If "that" were not present, then the second clause could stand alone as a complete sentence and the use of a comma would not be sufficient to separate the two clauses of the sentence.

I hope this helps :)

Feb 26, 2016 • Reply


Joo Hyun Oh

So I guess this questions shows us that "not just A but also B" is also an acceptable form of "not only A but also B" ?

Plus, I was wondering whether the omission of "also" when using the above phrases, like in answer choices A and C, can rule an answer choice out?


Aug 5, 2015 • Comment

Jonathan , Magoosh Tutor

Right: "not just A but also B" is also correct.

"not just A but B" is incorrect.

"not A but B" could be correct.

Please see the following posts:

Our ebook:

Hope this helps1

Aug 11, 2015 • Reply


Gravatar Mike McGarry, Magoosh Tutor

May 23, 2013 • Comment

Jithin Mathew

Dear Mike,
what is the scientist monitoring expanding cloud or large storm. I am not able figure out this. Kindly help.

Nov 1, 2013 • Reply

Lucas Fink

Hi Jithin,

It seems you posted this on the wrong page, accidentally--the question you're referring to is here:

And the good news is that you don't need to undestand the scientific context, only the structure of the sentence :-)

Notice this part of the sentence "...who monitored its path, an expanding cloud of energized particles ejected from the Sun...". The word "its" logically refers to the nearest logically possible noun, which is, in this case, the expanding cloud. So that's what they monitored.

Hope that helps!

Nov 9, 2013 • Reply

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