Sentence Correction

To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economic

OA = D...can someone please tell what is wrong with A and E ?

goelmohit2002 wrote:To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economic

OA = D...can someone please tell what is wrong with A and E ?

The answer should use "would". It is a condition actually. To develop.... Demographers "should"/"would have to" know blah blah blah.
So A and B are out.
One more reason to kick A out is the parallelism factor. "Demographers would have to know more than now". would have to know is being compared with "now". That is not correct.

Let's check C, D and E now.
C --> "economical" changes the meaning.
D --> Correct.
E --> Parallelism. would have to know is being compared with "now".

Please let me know if this explanation is helpful.


Thanks.

riteshbindal wrote: The answer should use "would". It is a condition actually. To develop.... Demographers "should"/"would have to" know blah blah blah.
So A and B are out.
One more reason to kick A out is the parallelism factor. "Demographers would have to know more than now". would have to know is being compared with "now". That is not correct.

Let's check C, D and E now.
C --> "economical" changes the meaning.
D --> Correct.
E --> Parallelism. would have to know is being compared with "now".

Please let me know if this explanation is helpful.
Thanks.

Thanks Ritesh !!!

Can you please tell why would/should is required...is there a grammar rule for the same ?

Also can you please tell why comparison is wrong....there are couple of examples in OG where they kick out answer based on the reasoning that you too gave....but sometimes they accept the same...saying that comparison is implicit...I suppose that is known as elipse....can you please help me understand when dropping is fine and when it is not(as is the case in this question)?

goelmohit2002 wrote:

riteshbindal wrote: The answer should use "would". It is a condition actually. To develop.... Demographers "should"/"would have to" know blah blah blah.
So A and B are out.
One more reason to kick A out is the parallelism factor. "Demographers would have to know more than now". would have to know is being compared with "now". That is not correct.

Let's check C, D and E now.
C --> "economical" changes the meaning.
D --> Correct.
E --> Parallelism. would have to know is being compared with "now".

Please let me know if this explanation is helpful.
Thanks.

Thanks Ritesh !!!

Can you please tell why would/should is required...is there a grammar rule for the same ?

Also can you please tell why comparison is wrong....there are couple of examples in OG where they kick out answer based on the reasoning that you too gave....but sometimes they accept the same...saying that comparison is implicit...I suppose that is known as elipse....can you please help me understand when dropping is fine and when it is not(as is the case in this question)?

Hi Mohit,
Not sure about grammar rule. But I am sure, you may find one in Manhatten SC that if we are talking about some thing which is not sure, we should use "would".
Even if you don't want to use it, A can also be removed due to parallelism as we did it in sme other choices too.
I am not sure about those answers in which OG is not kicking out the answers even if it does not have correct parallelism. May be, I can see some examples to check if there is any difference in those questions.

it's not so much that "would" is necessary but that all other answers are wrong besides D

"economical" is wrong, so B C are out.
"than now" is wrong, so A E are out.
So only D is left behind.

Whether "would" is used, the meaning is changed slightly but that's not the deal breaker in this question.

I think ritesh is bang on !!!

This is the case of hypothetical...so we need to use....would....

Other reasons too I think are good reasons to kick out options...

To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

the bolded part indicates that its a case of subjunctive mood , so it requires conditional verb would have and out of C D and E agree with ritesh

for more information check this link

https://gmat-grammar.blocked/2006/0 ... verbs.html

goelmohit2002 wrote:To develop more accurate population forecasts, demographers have to know a great deal more than now about the social and economic determinants of fertility.

A. have to know a great deal more than now about the social and economic
B. have to know a great deal more than they do now about the social and economical
C. would have to know a great deal more than they do now about the social and economical
D. would have to know a great deal more than they do now about the social and economic
E. would have to know a great deal more than now about the social and economic

OA = D...can someone please tell what is wrong with A and E ?

E does not work because "than" sets up a comparison that is unbalanced in this case. "now" is an adverb that's being compared to "know"ing, a verb. However D, sets up a comparison that is balanced, "know"ing and "do"ing.

you got this man!