Question

【题目】—Is Jason all right? He looks so tired!

—Not sure. He __________ deep into the night yesterday. He's having an exam soon.

A. may have studied

B. should have studied

C. might study

D. must have been studying

Answer 1

【答案】A

【解析】表示对过去发生的情况的推测，应该用may/might have done 结构。should have done 意为“本应该做某事而没做”，must have been doing 表示对过去某段时间内一直在进行的动作的肯定推测。