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.

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