The United States will be affected by whether Taiwan develop

[Suapplle]

Is there grammar error with D?

at least two.
1 the pronoun 'it' doesn't have an antecedent. there are certain idiomatic constructions in which a standalone 'it' is allowed (such as 'make it difficult to...'), but this isn't one of them.
2 bad parallelism: 'will develop' is in the future tense, but 'preserves' is in the present tense. as they are alternatives in a decision, these must be presented in the same tense.

If not, what makes it less good as A?

just so you know, you have to use than (not 'as') with less (the gmat loooooooves that distinction, so know it!).

also, you can't say 'less good' in formal written english (the correct word is 'worse').

Hi,Ron,I am still confused about two things.
first,in choice D, can "it" refer to "whether Taiwan will develop a closer......"?
second，the difference between "whether...... or......" and "whether or not".
please help,thanks a lot!

[RonPurewal]

first,in choice D, can "it" refer to "whether Taiwan will develop a closer......"?

That isn't a noun, so, no.

second，the difference between "whether...... or......" and "whether or not".
please help,thanks a lot!

"Whether or not xxxxxx" is redundant.

[samwong]

there are two ways to use "whether", and the meaning of the sentence will dictate what the acceptable uses are. if we want to know whether Taiwan will do something (in this case that something is X or Y), the parallel marker is just "or" and the "whether" applies to the entire phrase with the parallelism inside it. in this case it does not matter where the parallel element on the left starts..

on the other hand, if Taiwan has a choice between two options (X or Y) and we are not sure which it will do, then the "whether" forms part of the parallel marker together with "or". in this case, the word after "whether" must match the word after "or"..

from a geopolitical perspective, i disagree with the way this sentence is presented and think there should be a "Taiwan" after the "or" to make the sentence conform to the second scenario i listed above. however, you are not supposed to bring outside knowledge of international relations into the problem. the bottom line is, if you are unsure of the intended meaning from within the context of the sentence, don't eliminate an answer choice that could be correct under one of these interpretations. the other thing to consider is that if you're unsure of which interpretation to use, you may want to address a different issue in the problem. all the other answer choices are clearly wrong for other reasons, so we are stuck with A and the resulting interpretation that flows from it having been written the way it was..

Merry Christmas to all the MGMAT Staff and test takers!

I'm sorry, but I'm a little confused about Tim's explanation on the two possible usages of "whether...or...". I don't see the difference between the two usages. Tim said that "Whether Taiwan develops...or Taiwan preserves..." implies that Taiwan has a choice between two options and you are not sure which it will do. First, it seems redundant to repeat "Taiwan" after "or". Second, is Tim implying that in the first "whether" usage (Whether Taiwan develops...or preserves...) you do know which it will do.

Can you please make up a sentence for each of the "whether" usage to illustrate Tim's point.

Thank you.

[RonPurewal]

If whether is used to connect two verbs/actions, I'd keep it simple and just analyze all such situations with "or" as the parallel marker.
I.e., while Tim may well be right about the distinction, I don't think it needs to be made. Just find the two parallel structures connected with "or".

--

If whether is used to connect two nouns, THEN I'd consider both "whether" and "or" as parallel markers.
E.g., Everyone in the country, whether civilian or soldier, was in danger during the war.

Otherwise you can just pay attention to "X or Y".