—What's the matter with the man hanging his head there?—Well if you know he was caught s

问题补充：

—Whats 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

答案：

(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。