题目内容：

I would like to be a policeman,____who are in trouble.
A.helps these
B.helping those
C.help those
D.helping one

优质解答

B,非谓语动词的运用,逗号之后且没有and等连接词连接,说明后面是非谓语动词形式,不能是动词原型,排除AC,再通过后面的定语从句中的谓语动词are判断,前面先行词应该是复数,因为定语从句的谓语动词和先行词一致,所以前面是those,而不能是one.