781.I ____ have watched that movie-it'll give me horrible dreams.
A.shouldn't
B.needn't
C.couldn't
D.mustn't
782.May I take this book out of the reading room?
No,you _____.You read it in here.
A.mightn't
B.won't
C.needn't
D.mustn't
781.答案是A;shouldn't have done,本来不应该做而做了某事；needn't have done本不必做而实际上做了；couldn't have done表示退推测，不可能干了某事。此题根据下文暗示，应选A。
782.答案是D;英语中may或might征求意见的问句，其否定回答要用mustn't。
