It be the vocabulary that caused you the problem in the exercise because you know a lot o

问题补充：

It be the vocabulary that caused you the problem in the exercise because you know a lot of words.

A. may

B. couldn’t

C. should

D. needn’t

答案：

A. may

(答案→)B. couldn’t

C. should

D. needn’t

解析：考查情态动词：A、可以；可能；B、不会，不可能；C、应该；D、不必。句意：不可能是词汇导致你在考试中出这个问题，因为你知道很多单词。结合语境可知选B。