Need and Needn’t.ppt

一、need作情态动词的用法： 1 need用作情态动词时表“必须必要”的意思，后直接跟动词原型，且need无人称、数的变化（第三人称单数不加s），也没有非谓语形式（不定式、分词）。注意: 2 need用作情态动词时常用于否定句和疑问句中。例：Need he bring his laptop tomorrow?明天他必须带他的笔记本过来吗？Come on , you neednt worry about it becuse its not your fault.行啦，你不必担心的因为那不是你的错。 must引导的一般疑问句的否定回答必须使用neednt。-Must I leave?我必须离开吗？-No,you neednt.不，你不必离开。 ;二、need作实意动词的用法：  1、need+something需要某物 例：I need some fruits to eat.我需要些水果来吃。 2、need to do something需要做某事 例：You dont need to have the bike repaired right away.你不必马上去修车。 3、need doing=need to be done需要……例：Theroomneedscleaning=Theroomneedstobecleaned.房间需要打扫了。 4、need some body to do something需要某人做某事例：I need some one to help me out of this problem.我需要找人来帮助我解决这个问题。; 三、need作名词的用法：need用作名词时，既可以是可数名词，也可以是不可数名词。主要常用句型如下： 1、(Theres)no need to do something没必要做某事 例：Theres no need to cover such along distance.没必 要走那么远的距离。 Theres no need for me to break the window because I have the key.我没必要打破窗户因为我有钥匙。 No need to run since were not pressed for time.不必跑 啦，我们又不赶时间。 也可以单独使用：Theres no need.意思是“没有必要”。 2、in (great) need of（非常）需要 例：There scue team is in great need of medicine.救援 小组非常需要药品。 3、if need be如果需要的话 例：If need be,Im going to do you a favor.如果需要的话我会帮你的。;1.Needn’t=don’t have to .needn’t expresses absence of obligation.表示没必要做的，没有义务做 eg:you needn’t do the whope exercise now.You can finish it at home 2.The past from of neednt is didn’t need to do eg:Since she helped with the heavy bag,l didn’t need to take a taxi. 3.The alternative past from of didn’t need to =needn’t have + -ed participle. It is used when an action has been unnecessarily done. ;eg:The needn’t have waited for us in the rain.