Mary ________ about her school work.

问题描述:

Mary ________ about her school work.
A.doesn't B.needs not worry C.needn't worry D.needn't to worry

need to do sth时need是实义动词
need do sth时need是情态动词
当实义动词动词用时多用在肯定句中
当情态动词用时多用在否定句和疑问句中
这里应该选C