He looked around and caught a man his hand into the pocket of a passenger.
A. put
B. to be putting
C. putting
D. to put
网友回答
A. put
B. to be putting
(答案→)C. putting
D. to put
解析：整句话的意思是：他环顾四周，偶然撞见一个男人把手放进了一位顾客的口袋里！固定句型catch sb. doing sth 偶然撞见某人在干某事~~~，这里的现在分词是做宾语补足语，强调动作的主动和进行，所以选C。