. --- I'm 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
网友回答
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。