1.need作实义动词，意为"需要"。如：

　　Do you need to stay at home?　　　你要呆在家里吗？

　　2.need作情态动词，一般用于对must的否定回答。如：

　　---Must he leave now?　　他必须离开吗？

　　---No, he needn't.　　　　不，他不必。

　　3.区分：

　　a.need作实义动词。

　　He needs to go.

　　He doesn't need to go.

　　Does he need to go?

　　Yes, he does./No, he doesn't.

　　b.need作情态动词，一般不用于肯定句。

　　He needn't go.

　　Need he go?

　　Yes, he need./No, he needn't.