答案A为什么,C为何不可以?

问题描述:

答案A为什么,C为何不可以?
If you want to improve your listening skills,you should often _____tapes after class.
Alisten to B listen C listens to D hear

C 是动词第三人称单数形式,这里是情态动词should之后,不论人称都是动词原形.