— 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：情态动词must在此表示“偏要，硬要”。句意：在那边垂着头的人怎么了？——如果你偏要知道的话（那我就告诉你），他在偷我自行车的时候被捉住了。