2012高考英语语法金点拨：情态动词
一．情态动词的语法特征
1） 情态动词除ought 和have 外，后面只能接不带to 的不定式。 2） 情态动词没有人称，数的变化，即情态动词第三人称单数不加-s。 二．情态动词的用法（Can/could、May/ might、Must、Shall/should、will/would、Dare、Need、ought to）
（一）. Can
1.基本用法
1）表示能力 The parrot can speak three languages.
2）表示请求/允许 Can/Could I borrow the book from the library.Yes.I can/No.I can’t。 (Could 不表过去式；只表语气更委婉，表请求只用于疑问句)
3）表示可能性 Shanghai can be very cold in March.
2. Can 与 be able to
1）can could 表示能力；可能 (过去时用could)
2）表示过去成功地做了某事时，只能用was/were able to， 不能用could。 He was able to flee Europe before the war broke out. = He managed to flee Europe before the war broke out.
3）在否定结构中，二者可以互换。
3. can/could + have +p.p
1）在否定、疑问句中表示“对过去发生行为的可能性猜测。
The door was lacked. She couldn’t have been at home.
2）在肯定句中表示“本来可以做而未做” You could have been more careful.
4.习语：cannot / can’t（never/hardly）do…too …“越……越好，怎么也不过分”。
You cannot be too careful when you drive a car.驾车时候，越小心越好。
（二）. May
1.基本用法
1）表示可能性 She may be still waiting for us.
2）表示允许 May I come in? Yes, you may./No, you mustn’t.
3）表示祝愿 May you have a happy holiday
Might 过去式；语气更委婉
2. may/might + have +p.p
1）在否定、肯定句中表示对过去动作的推测 “也许是……”He might have spoken to her yesterday.
2）Might+have+p.p表示虚拟，表“劝告、责备之意。” You might have told me earlier.
3.习语： may/might as well do sth，意为"不妨"。 If that is the case, we may as well try. （三）. Must
1.基本用法
1）表示肯定的猜测,但只用于肯定句，
You have worked hard all day.You must be tired. 你辛苦干一整天，一定累了。
He must be working in his office. 他一定在办公室工作呢。
2）而mustn’t 表示“禁止、不准”
John, you mustn’t play with the knife, you may hurt yourself．
3）must用于疑问句，表示责备、抱怨的感情色彩，意思为“偏偏，偏要”
John, look at the time.Must you play the piano at such a late hour?
2. Must 、have to
1）Must表示主观 He said that they must work hard.
2）Have to表示客观需求
My brother was very ill, so I had to call the doctor in the middle of the night.
3. must + have +p.p对过去事情的肯定猜测。 The road id wet. It must have rained last night.
4.Must I hand in the book now? Yes, you must./No, needn’t /don’t have to.
（四）Shall /should
1.基本用法
1）第一、三人称疑问句中表示“请求或征求对方意见。Shall I get you a cup of coffee?
2）第二、三人称陈述句中表示许诺、决心、命令或警告。
You shall lose your job if you don’t do as I tell you．如果你不按我说的做，你将失去工作
You shan't have my computer if you don't take care of it.
3）shall/should / ought to + have +p.p 表示本应该做而未做。 You should have been five minutes ago.
shall/should / ought (not)to + have +p.p 表示本不应该做而做了。
The little boy shouldn't have eaten the apple without washing it first.这个小男孩不应当不洗苹果就吃。
（五）Will/ would
1.基本用法
1）表示意愿 I’ll try my best to overcome the difficulty.
2）表示意图 What will you do?
3）表示请示 Will you halp me to put these books in order?
4）表示习惯动作She will sit for hours without saying a word.
2.Would 与 used to
1）Would表示过去反复发生的动作或某种倾向,后只能接表示动作的动词。
He would go to that coffee shop at the corner after work every day.
2）used to 则还可以接表示状态的动词。He used to be a worker.
（六）Dare / dared
1.基本用法
1）作为情态动词用于否定、疑问句；条件从句中。
1. Dare you go here alone? 2. How dare you do such follish things?
3. I won’t allow you to swim in the river, even if you dare do it.
2）做实意动词后加不定式。 I have never dared to tell him about it.
（七）Need /needed
1.基本用法
1）、情态动词用于否定句，疑问句。 2）、实意动词用法似dare,用作不定式。
3）、need + not + have +p.p 表示“本来不需要做而做了。
You needn't have brought your umbrella.It is going to be clear up.你本可以不必带伞，天就要晴了。
2.在一般疑问句中的回答： Need I finish it now? Yes, you must./No, you needn’t.
典型错误
1. He mustn’t be in the classroom. (Can’t )
2. You might leave the bag on the bag. (might have left )
3. You must have seen the film last week, have’t you? (didn’t you )
4. Li ming must have been to Japan, didn’t he? (hasn’t he )
（ 表推测的反义疑问句要根据原时态或时间词确定助动词）
注：情态动词+动词不定式表推测的用法比较
（一）情态动词+动词原形表推测的用法
1.肯定的推测一般用must,should,may(might)或could(不用can)，其中，must的语气最强，译为“肯定”、should的语气次之，译为“很可能”、“应该”；按常理推测：may(might),could语气最弱，译为“也许”。
①Helen_____ go on the trip with us, but she isn’t quite sure yet. （05安徽）
A. shall B. must C. may D. can
② __ I've taken someone else's green sweater by mistake. (2005广东卷)
__It ______ Harry's. He always wears green.
A. has to be B. will be C. mustn't be D. could be
③Mr Bush is on time for everything．How＿ it be that he was late for the opening ceremony﹖
A.can B.should C.may D.must (2001上海春季卷)
④—Are you coming to Jeff’s party﹖ —I’m not sure．I go to the concert instead． (2000全国卷) A.must B.would C.should D.might
⑤—When can I come for the photos﹖ I need them tomorrow afternoon． —They ＿＿＿＿＿ be ready by 12:00.(98全国卷) A.can B.should C.might D.need
2.否定的推测：语气不很肯定时，常用may not,might not或could not，译为“可能不”“也许不”；否定语气较强时，则用can’t，译为“根本不可能”、“想必不会”，表示惊异、怀疑的感情色彩
①You might just as well tell the manufacturer that male customers_____not like the design of the furniture.
A.must B.shall C.may D.need (2004上海春季卷)
②—Do you know where David is? I couldn’t find him anywhere. （2005湖北卷）
—Well . He have gone far—his coat’s still here.
A.shouldn’t B.mustn’t C.can’t D.wouldn’t
3.疑问句中推测往往用can或could
Mr.Bush is on time for everything.How_____it be that he was late for the opening ceremony?
A.can B.shoul C.may D.must (2001上海春季卷)
（二）情态动词+have done表推测的用法
must have done： 表示对过去动作的肯定推测，常译作“一定……”，只能用于肯定句中。其否定形式为can’t／couldn’t have done 疑问式为Can／Could...have done﹖。 could ／might have done：表示对过去发生的动作的可能性推测，常译作“可能做了……”。
①He___ have completed his work; otherwise, he wouldn’t be enjoying himself by the seaside.
A. should B. must C. wouldn’t D. can’t (2005北京卷)
②—Do you know where David is? I couldn’t find him anywhere. （2005湖北卷）
—Well . He have gone far—his coat’s still here.
A．shouldn’t B．mustn’t C．can’t D．wouldn’t
③My sister met him at the Grand Theater yesterday afternoon, so he your lecture．
A.couldn’t have attended B.needn’t have attended C.mustn’t have attended D.shouldn’t have attended (2000上海卷)
【点此下载】