问题补充：
If you are in trouble, you can help from the policeman.
A. look over
B. ask for
C. check
D. think about
答案：
A. look over
(答案→)B. ask for
C. check
D. think about
解析：
试题分析: 句意：如果你有困难，你可以求助于警察。 look over检查，ask for请求，check检查，think about考虑。根据If you are in trouble如果你有困难，可知是有困难找警察，故选B.
