Tom's mother kept telling him that he should work harder, but ______didn't help．

A.he

B.which

C.it

D.one

答案及解析： C

试题分析：句意：汤姆的妈妈一直告诉他他应该更加努力学习，但那没用。从题目中可以看出这是并列句，it指代Tom's mother kept telling him that he should work harder.整句话。所以选A。

考点: 考查代词的用法。