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Augustus DeMorgan

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by PGMAT » Sun Jun 17, 2012 11:01 am
Augustus DeMorgan made many valuable contributions to calculus, trigonometry, algebra, and logic; but perhaps his most famous academic contribution, a pair of theorems concerning complementation of sets, is still known today as DeMorgan's Rules.
A. a pair of theorems concerning complementation of sets, is
B. a pair of theorems concerning complementation of sets, are
C. two theorems that have to do with complementation of sets, are
D. two theorems that define complementation of sets, is
E. two theorems that are both related to complementation of sets, are

Can some one explain in detail why choice D/E is incorrect? If we say 'two theorems' then we need 'are', and thats what we have in choice E.
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by dimochka » Sun Jun 17, 2012 3:48 pm
"a pair of theorems concerning complementation of sets" is a more specific description of the academic contribution. Since this phrase is also separated a comma on each side from the rest of the sentence, you should be able to take it out, and the sentence should still make sense.

Look at E if we take it out: "...his most famous academic contribution are" - grammatically incorrect. You already have the correct are within that sentence: "two theorems that are both...". The second are refers to the contribution.

Additionally, both D and E are incorrect because we are talking about a contribution, which is singular. Thus the portion that specifically speaks of the contribution must be singular (ie. a pair of theorems).
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by vk_vinayak » Mon Jun 18, 2012 2:17 am
IMO A. a pair of theorems concerning complementation of sets is singular.

Please post the OA.
- VK

I will (Learn. Recognize. Apply)
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by dimochka » Mon Jun 18, 2012 6:41 am
Don't know OA but I agree with vk_vinayak
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