The train is to start soon and Mary hasn’t turned up． What have happened to her?
A. can
B. might
C. may
D. should
网友回答
(答案→)A. can
B. might
C. may
D. should
解析：考查情态动词表示推测。Can have done可能做了某事；might/may have done也许做了某事；should have done本不应该做某事；句意：火车就要出发了，Mary仍然没有出现。她可能发生了什么事情呢？根据句意是对过去发生的事情的推测。故A正确。