1、突破 语法大冲关UNIT 4 Exploring literature情态动词情态动词作为谓语的一部分，无人称和数的变化(have to 除外)；一般不能单独使用，要与谓语动词构成完整谓语，但在回答时，可单独使用。情态动词有 can(could)，may(might)，must，have to，shall(should)，will(would)，dare(dared)，need(needed)，ought to 等。观察思考 Today，both male and female athletes from around the world cantake part.I am sure all
2、Chinese must have felt proud when Xu Haifeng won the first gold medal for his country.Naturally，after I tell her what to do，my daughter must do the opposite!You should apologize to Mary for your rude remarks.Mr.Green must be a teacher，isnt he?He may come here by train，but I am not sure.Need I pay th
3、e whole amount now?There has to be a reason for his strange behaviour.归纳用法 1can(could)(1)表示能力，can 表示现在的能力，could 主要指过去的能力。You can tell the significance of climate change to us.你可以告诉我们气候变化的重要意义。名师点津 can 表示能力的时候，还可以用 be able to 代替，can用于一般现在时，could 用于一般过去时。can(could)表示具备这样的能力，但不一定做了；而 be able to 表示不但具备这
4、样的能力，而且经过努力做了。Can you come to the party tomorrow?明天你能来参加聚会吗？He was a good swimmer so he was able to swim to the riverbank when the boat sank.他是一个很擅长游泳的人，所以当船下沉时，他能够游到河岸上。(2)表示请求许可。当请求允许做某事时，两者均可用，但用 could 语气更委婉。当表示允许某人做某事时，一般要用 can，而不用 could。Can/Could I use your bike tomorrow morning?Yes，you can./No
5、.Im afraid not.我明天早晨能用你的自行车吗？是的，可以。/不，恐怕不行。(3)表示推测。can 表推测时一般用于否定句和疑问句中(could 一般无此限制)。表示对过去发生的行为怀疑或不肯定时，常用“can/couldhave过去分词”的否定或疑问形式。It cant/couldnt be true.那不可能是真的。We could go there this summer.今年夏天我们可能要去那里。(4)表示客观的可能性(并非主观推测)，意思是“有时候可能会”。The weather in Shanghai can/could be very cold in winter.上海
6、冬季可能很冷。(5)表示惊异、怀疑，不相信的态度(主要用在否定句、疑问句或感叹句中)。How can you be so careless!你怎么那么粗心呀！即学即练 1 选词填空：can，could，be able to Man _ not live without air.Being a wise person，he finally _ find the place.The cheater said that he _ turn stone into gold.can was able to could 2may(might)(1)表示允许，might 可以指过去，也可指现在，语气更委婉。
7、May(Might)I ask for a photo of your baby?我可以要一张你宝宝的照片吗？名师点津 对 may 的一般疑问句的肯定回答可用 may 或 can，但作否定回答时要用 mustnt 或 cant。May I smoke here?No，you mustnt./Youd better not.我可以在这里吸烟吗？不，不可以。/你最好不要吸烟。(2)表示可能。可以指过去，也可以指现在，但语气不肯定。She may not know about it.她可能不知道这件事。(3)用于表祝愿的句子中。May both the bride and groom be happ
8、y!祝新娘新郎幸福！3must(have to)(1)must 表示必须，没有时态变化。强调的是一种主观看法，也表示责任或义务。have to 表示“必须，不得不”，是由于某种外界(客观)原因而“必须，不得不”做某事，也可表示经常的或习惯性的事“必须”做。mustnt 表示禁止做某事；have to 的否定形式为dont/doesnt/didnt have to 表示“不必”。have to 可用于多种时态中。My brother was very ill，so I had to call the doctor at midnight.我弟弟病得很厉害，我必须半夜里把医生请来。(客观上需要做这
9、件事)He said that he must work hard.他说他必须努力工作。(主观上要做这件事)名师点津 回答 must 引出的疑问句时，如果是否定的回答，不能用 mustnt，而要用 neednt 或 dont have to。Must we hand in our exercise books now?Yes，you must.(No，you neednt./No，you dont have to.)我们现在就必须要交练习本吗？是的，必须。(不，不必。)(2)must 表示猜测。意为“想必，准是，一定”等，只用于肯定句。Shes wearing a diamond neckla
10、ce.She must have a lot of money.她戴着钻石项链，一定很有钱。(3)must 还可表示“偏要”。表示说话人不耐烦、不满的情绪。Why must it rain on Sunday?为什么偏要在星期天下雨？即学即练 2 用适当的情态动词填空 My sister is ill，my mother _ look after her.Theres a lot of noise from next door.They _ be having a party.Must I return all the books in three days?Yes，you _(No，you
11、_)If you _ go，at least wait until the storm is over.has to must must neednt/dont have to must 4shall(1)表示征求意见，用于第一、第三人称疑问句。Shall I get you some more tea?再来点茶好吗？(2)表示说话人的意愿，有“命令、允诺、警告、决心”等意思，用于第二、第三人称陈述句。You shall come on time.你必须准时到。(命令)He shall have the book when I finish reading it.我读完这本书就给他。(允诺)N
12、othing shall stop us from carrying out this plan.没有什么事情能阻止我们实施这项计划。(决心)(3)shall 用于第三人称，表示按照法律、条文或规定必须做的事，意为“应，必须”。No reader shall remove a book from the library without permission.未经许可，读者不准把书带出图书馆。即学即练 3 选择下列句中 shall 的含义 A允诺 B警告 C威胁 D征求意见 You shall fail if you dont work harder._ You shall get an ans
13、wer from me tomorrow._ You shall be punished for what youve done._ Shall I watch TV for a while？_ B A C D 5should(1)表示义务、责任。意为“应该”(某件事宜做)，用于各种人称。You should be polite to your teachers.你对老师应该有礼貌。(2)表示可能性很大的猜测，意为“想必一定，照说应该，估计”等。The film should be very good as it is starring first-class actors.这部电影是一流演员
14、主演的，估计拍得很好。(3)表示说话人的惊讶、愤怒、失望等特殊情感，意为“居然，竟然”。Amazing！You should wear slippers at work.真令人惊讶，你竟然穿着拖鞋上班。6will(would)(1)表示意志或意愿。will 指现在，would 指过去，用于否定句表示“不肯，不乐意”。I will never do that again.我决不会再做那种事了。(2)表示征求意见或提出请求。主要用于第二人称疑问句中，will和 would 均可用，would 此时不表示过去，而是表示委婉语气。Will/Would you pass me the book plea
15、se?请你把书递给我好吗？(3)will 和 would 可分别表示现在和过去反复发生的动作或某种倾向，意为“总是；常常”。He will sit up there all night.他总是整夜坐在那儿。I said I would do my best.我表示过要尽最大努力。明辨异同 used to，would used to指过去的动作或状态，着重与现在的对比，可以与过去时间状语连用 would表示过去的情况，指过去的习惯性动作，不说明现在的情况 即学即练 4 用适当的情态动词填空 _ you please save some dessert for me?He _ be a very
16、strong man，but now he isnt.We _ sit in the yard every evening and listen to his stories when we were young.Will/Would used to would 7ought to(1)表示职责和义务，意为“应该”(因责任、义务等该做)，口气比 should 稍重。You oughtnt to smoke so much.你不应该抽这么多烟。(2)表示推测，暗含很大的可能性，类似于 should。Han Mei ought to know his telephone number.韩梅应该知道
17、他的电话号码。8need 和 dare(1)它们作情态动词时，后跟动词原形，常用于否定句、疑问句中。一般不用于肯定句，无第三人称单数形式。dare 有过去式形式，构成疑问句时，将其移至句首；构成否定句时，直接在其后加 not。Need I tell him everything?Yes，you must./No，you neednt.我要告诉他一切吗？是的，必须。/不，没有必要。How dare she do things like that to me?她怎么敢对我做那样的事呢？(2)作实义动词时，其否定和疑问的构成需借助 do/did/does，need后面接带 to 的不定式，而在疑问句
18、和否定句中，dare 后可省去 to。有人称和数的变化。He didnt dare(to)go there.他不敢去那儿。Right now you need to stay still until help comes.现在你需要待着别动，直到有人来帮忙。即学即练 5 用 dare/need 的适当形式填空 You _ hurry.There is still enough time to go.Must I go right now?No，you _ How _ you say Im unfair?He _ speak English before such a crowd，dare he
19、?He _ to finish it this evening.Dont you _ touch it?neednt neednt dare darent needs dare 9情态动词表示推测或判断的用法 下表是表示推测的情态动词使用的场合：情态动词对现在和未来的推测对过去的推测使用场合 mustmust domust have done肯定句 may/mightmay/might domay/might have done肯定句、否定句 情态动词对现在和未来的推测对过去的推测使用场合 can/couldcan/could docan/could have done否定句、疑问句(coul
20、d 可用于肯定句)shouldshould doshould have done肯定句、否定句、疑问句 情态动词have done 的用法(1)should/ought to have done 表示“本来应该做某事而实际上未做”，而 shouldnt/ought not to have done 则表示“本不应该做某事而实际上做了”。You should/ought to have told me about it earlier.关于这件事你本应该早点告诉我的。You shouldnt/ought not to have said such words to your parents.你本
21、不应该给你父母说这样的话。(2)neednt have done 表示“本无必要做某事而实际上做了”。You neednt have walked so quickly since time was enough.你本来不必走这么快的，时间很充足。(3)could have done 表示“本来可以做某事而事实上未做到”。I could have come on time，but my car broke down on the way.我本来可以准时到的，但是我的车在路上坏了。(4)may/might have done 表示“可能发生过某事”或“本来也许可以做某事(实际上没做)”。You
22、might have given him more help，but you were so busy.你也许可以给他提供更多帮助的，但你太忙了。即学即练 6 补全句子 I _(我本来可以帮助你的)，but I was too busy then.You _(一 定 是 睡 得 很 晚)last night.Your eyes are red.You know the story very well.You _(可能读过它)before.could have helped you must have gone to bed late may/might have read it.单句语法填空
23、1It is strange that such a famous poet _ be so rude to a lady.2You _ come here on time，or youll be fined next time.3I _ have cooked so much food.Nobody was hungry.4He told me he _ be free tonight.should must neednt would 5I _ finish reading the novel tomorrow，but I am not sure about it.6You _ to hav
24、e given him some advice.He was too upset at that time.7It is a long time since we met last time.You _ come and see me more often.may/might ought should 8She was so frightened that she didnt dare _(breathe)a word of it to anyone else.9He finished all the work himself;in fact,he _ have asked his frien
25、ds for help.10You _ feel all the training a waste of time，but Im a hundred percent sure later youll be grateful you did it.(to)breathe could may.短文语法填空 Lucy is an outgoing lady.She 1._ play many kinds of musical instruments.Actually，she 2._ play the piano when she was 8 years old.Lucy also keeps tak
26、ing exercise every day.She says that she has to do some sports because she 3._ keep slim.“You 4._ get fat soon if you dont take exercise every day.”She usually says to her friends.can could must shall As for her，an elegant lady should try to keep fit.However，last week，she found that she 5._ put on w
27、eight and her husband suggested that she 6._ lose weight.However，she is always lacking in time because she has to take care of her children.One night after supper，she walked quickly to go dancing at the park.On her way，she thought that the dancing must 7._(begin)and the coach 8._ have taught many new moves,but the coach was absent that night,so she was regretful.might should have begun could 谢谢观看 THANK YOU!