问题补充:
. --- Im sorry. I the bike to you yesterday. But I was too busy at that time.
--- Never mind.
A. should return
B. should have returned
C. must return
D. may have returned
答案:
A. should return
(答案→)B. should have returned
C. must return
D. may have returned
解析:考查情态动词的用法,因为说的是昨天的事,用情态动词+have done,它们指的都是过去的情况,should have done本应该做而没做,may have done本可以做,句意是:对不起,我本应该昨天把自行车还给你的,但我太忙了。选B。