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Augustus DeMorgan made many valuable contributions to [#permalink]

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21 Sep 2012, 22:40

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A

B

C

D

E

Difficulty:

45% (medium)

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53% (01:53) correct
47% (00:55) wrong based on 320 sessions

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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

Re: Augustus DeMorgan made many valuable contributions [#permalink]

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22 Sep 2012, 04:17

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The subject ‘contribution’ plays a key role in deciding the answer here. First being a singular subject, the subject’s verb also should be singular –i.e.: is, dismissing B, C and E. Second, the singular subject entails a singular appositive modifier, namely, a pair as in A and not two theorems as in D. Hence A .
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Re: Augustus DeMorgan made many valuable contributions [#permalink]

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23 Sep 2012, 07:47

I chose A for the following reasons: 1. the Qn has non-essential modifier marked with ",". Thus we can disregard it. Subject contribution, verb is known as contribution is singular. Options A and D left; 2. Verb define in option D changes the meaning the sentence - we don't know for sure, whether they defined or concerned complementation of sets. Option A left.

Re: Augustus DeMorgan made many valuable contributions to [#permalink]

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26 Aug 2014, 14:38

Hello from the GMAT Club VerbalBot!

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Re: Augustus DeMorgan made many valuable contributions to [#permalink]

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27 Aug 2014, 20:36

daagh wrote:

The subject ‘contribution’ plays a key role in deciding the answer here. First being a singular subject, the subject’s verb also should be singular –i.e.: is, dismissing B, C and E. Second, the singular subject entails a singular appositive modifier, namely, a pair as in A and not two theorems as in D. Hence A .

I am confused with choosing A or D. It helps me answer my question. Thank your for exp. +1 kudos
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Re: Augustus DeMorgan made many valuable contributions to [#permalink]

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01 Sep 2015, 02:21

Hello from the GMAT Club VerbalBot!

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Re: Augustus DeMorgan made many valuable contributions to [#permalink]

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07 Sep 2015, 09:30

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.

his most famous academic contribution-------> Contribution referes to Singular Object...

So the decision point isIS / ARE

The correct answer will include IS , Only OPtions (A) and (D) are available...

(D) two theorems that define complementation of sets, is ----> Two theorems............must be are

(A) a pair of theorems concerning complementation of sets, is -----> A pair of ........ is (Correct)

Hence (A) is the best choice...
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Augustus DeMorgan made many valuable contributions to [#permalink]

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05 Mar 2016, 10:59

Quote:

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

Subject-verb combination quickly eliminated B, C and E due to plural verb are.

Coming to A and D, both are different in meaning.

Quote:

Concern means Relate to; the story concerns a friend of mine (be concerned with) this fable is concerned with forgiveness and redemption

MORE EXAMPLE SENTENCES Of course, the Today Tonight story was only concerned with the latter issue. Julian Barnes's new book of short stories is concerned with old age and death.

a pair of theorems related to complementation of sets is not the same as two theorems that define complementation of sets since we do not know whether theorems are just related to the complementation of sets or they define complementation of sets. We cannot assume so go for A. _________________

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Re: Augustus DeMorgan made many valuable contributions to [#permalink]

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05 Mar 2016, 11:40

subject ‘contribution’ plays a key role in deciding the answer here. First being a singular subject, the subject’s verb also should be singular –i.e.: is, dismissing B, C and E.

answer A .
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Re: Augustus DeMorgan made many valuable contributions to
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05 Mar 2016, 11:40

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