e-GMAT wrote:

gmatnerd wrote:Thanks for the insight on DCs .i didnt know the mechanics before.After analysing the sentence with these rules,i felt "know" is working as the verb for the clause(ignoring the noun modifier).Please help me if i am missing something.
The reason i am dwelling too much in to the wrong answer is because, there is no point in solving lot of questions without knowing why a wrong answer is wrong and how can it be corrected.

Thanks in advance

Hi,
You are absolutely correct. We must have valid reasons to eliminate a choice.

Coming to your query, a verb must have a subject and vice-versa. Presence of the subject-verb pair is mandatory to form a clause, either IC or DC.

"did not know" in the original sentence is the verb. So what's the subject for this verb? Who "did not know"? The answer is "Theodore C. Sorensen". He did not know about this recording system that was secretly installed and operated in the Kennedy Oval Office. So the subject-verb pair in the IC is "Sorensen" - "did not know".

In the DC, the verb is "was installed and operated"? What "was installed and operated"? The answer is "A recording system". Hence the SV pair in the DC is "A recording player" - "was installed and operated".

So remember that a verb MUST pair with subject to form a clause. A verb does not function as a verb for a clause.

Hope this helps.
Shraddha