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。
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