There's so much good stuff in this one: we have parallelism, a classic issue between “like” and “such as”, and a funky little comparison issue. For more on parallelism and meaning, check out this YouTube webinar; if you want more on that funky little comparison issue, then you might want to suffer through this video instead.


The GMAT gave us a nice little gift here: “like” generally isn’t be used to introduce examples on the GMAT – or at the very least, “such as” is preferred over “like” in every official question that gives us the option. For that reason, you could eliminate (A). (Full disclosure: there is an official GMAT question that uses “like” to introduce examples in the correct answer choice. But all five answer choices include “like”, and none offer “such as” as an alternative. So it’s a non-issue in that particular question.)

For whatever it’s worth, there’s also a parallelism issue here: “…sources like tar sands, heavy oil, and perhaps even in shale than…” Whoa, that doesn’t work: “tar sands” and “heavy oil” are nouns, but the parallelism trigger “and” is followed by “in shale” – a prepositional phrase. So that would be enough to eliminate (A), also.

But wait, there’s more: check out that comparison. “… ten times as much petroleum exists in [non-conventional sources] than in conventional reservoirs…”

That’s wrong: we could say that “ten times as much petroleum exists in [non-conventional sources] as in conventional reservoirs…” We could also say that “ten times more petroleum exists in [non-conventional sources] than in conventional reservoirs…” But “ten times as much… than” is definitely wrong.

So that’s three glorious reasons to eliminate (A).


(B) is exactly the same as (A), other than adding the word “are” at the end of the underlined portion – and that little difference doesn’t do anything to change the three reasons why (A) is wrong. So (B) is wrong for the same three reasons.

And in case you’re wondering about the word “are”: it does nothing productive for us here. The heart of the comparison is the idea that “ten times as much petroleum exists in [non-conventional sources] as in conventional reservoirs…” So there’s no good reason to stick the “are” in there: “ten times as much petroleum exists in [non-conventional sources] as are in conventional reservoirs…” It might be acceptable to repeat the word “exists” instead of “are”, but even that is unnecessary – and it’s just awkward and a waste of words to stick “are” into the sentence, when we’re really just comparing the phrase “in tar sands, heavy oil, and shale” with “in conventional reservoirs.”

But you could ignore that last paragraph, and have tons of reasons to ditch (B).



The “such as” is better, but there’s still a parallelism issue here: “…sources like tar sands, heavy oil, and perhaps even in shale than…” Just like in (A), that doesn’t work: “tar sands” and “heavy oil” are nouns, but the parallelism trigger “and” is followed by “in shale” – a prepositional phrase.

And the use of “are” in the middle of the comparison is still a mild problem, too. See my explanation in (B), above.

So (C) can be eliminated.

Let’s line (D) and (E) up side-by-side to make it easier to see the issue:


Yup, this is exactly the same problem as we saw in (A) and (B): because the comparison begins with “ten times as much”, we need to finish the phrase with “as”, not “than.” See the explanation for (A) if you need more detail on this.

So (E) is out, and (D) is our answer.
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IMO D.

A and B are out because we need "such as" for the examples. "Like" for this purpose is not correct.

C is out because there is no need to use the "are". The sentence has already a main verb.

E is out, because the comparison doesn´t need a"than", needs an "as"

D is the correct one since it corrects both errors: "such as" for the examples and uses "as" for the correct comparison. Ten times as much pretoleoum...as in conventional reservoirs

Hello juanito1985,


You have presented a good analysis of this official question. Keep up the good work.

However, I have a few things to add to your analysis.




It is a common understanding that like is used to present comparison and such as to present examples.

However, there are a few official sentences in which like has been used in the non-underlined portion of the sentence to present examples. Hence, rejecting any answer choice only on the basis of usage of like to present examples is not advisable.

Choice A is certainly incorrect for the usage of incorrect idiom as X than Y. Choice E can also be rejected for this reason.

In Choice B, usage of plural verb are is incorrect because:

i. are does not agree in number with the subject petroleum.
ii. the option needs a verb in place of exists to maintain the parallelism. Hence, we need the helping verb does to express an action (exists).





Choice C repeats the error the helping verb error of Choice B.

Also, use of preposition in is also incorrect in this Choice because the sentence intends to say that petroleum exists in such sources as x, y, and z. There is no need for nay preposition before any example.


Hope this helps.
Thanks.
Shraddha
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