—What's the matter with the man hanging his head there?
—Well，if you know, he was caught stealing my bike.
A. must
B. may
C. can
D. shall
网友回答
(答案→)A. must
B. may
C. can
D. shall
解析：考查情态动词用法。Must必须，一定；非得；may也许；can能够，可能；shall表示征求对方的意见等。句意：—头耷拉着的那个人怎么了？—如果你费要知道，他在偷我的自行车的时候被当成抓住。这里的must指非得；偏偏；故A正确。