need的用法：

①need 是行为动词，need to do sth. 意为"需要做某事"

You need to take breaks away from the computer.

你需要离开电脑休息一下。

I need to get some sleep.

我需要睡会儿觉。

②need后接v. -ing形式，表示被动，此时主语常为物。

My bike is broken. It needs mending.

我的自行车坏了，需要修理。

③need做情态动词，意为"需要"， 后接动词原形。

以must开头的疑问句否定回答常用needn'。

needn't意为"不必"， 相当于don't have to.

－Must I finish my homework today?

今天我必须完成家庭作业吗？

－No,you needn't/don't have to.

不，你不必。

④need还可以做名词，意为"需要；需求"。

There's a growing need for new housing in many cities.

在许多城市，对于新住房的需求在不断增长。

eg:－Must I finish reading the book today, Mr.Brown?

－No,you_____. You can finish it in two days.

A.needn't

B.mustn't

C.can't

D.couldn't

解析： 考查情态动词辨析。句意：－布朗先生，我今天必须读完这本书吗？－不，你不（今天读完）。你可以两天后读完。以Must 开头的一般疑问句，其否定回答通常用 needn't.故选A.

－What a beautiful factory! I want to work in it.

－Well,workers_____ very much here.

A.need

B.are needing

C.are needed

D.will need

解析：need在此为实义动词。be needed为被动语态结构。所以选C。