Question

Mary ____do her homework first when she gets home.

A. is B. have to

C. has to D .are

 

Answer 1

C

【解析】

试题分析：句意：玛丽到家后得先做作业。Have to必须，不得不，后跟原形动词，当主语为三单时要变为has to。所以选C。

考点：考查情态动词。