Question

He ________ sleep, although he tried to, when he got on such a hunt for an idea until he had caught it

1. A.
   wouldn’t
2. B.
   shouldn’t
3. C.
   couldn’t
4. D.
   mustn’t

Answer 1

C
句意：當他尋找到他一直想找到的想法時，盡管他想睡，卻不能睡著。表“能夠”，用can/could。would “將，將要；愿意”；should“應該〔不問人稱，表示義務，責任〕；大概是，有可能”；must“必須；必然要，一定”。
【考點定位】考查情態(tài)動詞的用法。