1、Unit 1Discovering useful structures-Modal Verbs(I)1.情态动词有一定的意义，只表示期待或估计某事的发生，不能表示正在发生或已经发生的事情。2.没有人称和数的变化，即情态动词第三人称单数不加-s。3.不能独立使用，它和后面的动词构成谓语。4.情态动词 除ought 和have 外，后面只能接不带to 的不定式。5.情态动词没有非谓语形式，即没有不定式，分词，等形式。只作情态动词的can/could,may/might,ought to,must可情态可实义的 need,dare/dared可情态可助动词的 shall/should,will/wo
2、uld相当于情态动词的 have to,used to情态动词的语法特征must(1)表示必须，多处于义务、责任或强制命令(must提问，否定回答用neednt或dont have to).You must hand in your homework today.(2)mustnt 表示禁止。意思是“不许”、“不准”、“不可以”。You mustnt smoke here.(3)用于发生了某种于说话人的愿望相反、不受欢迎的事时，意思是“偏偏”、“偏要”。Why must he do it that way?Why must it rain on Sunday?4.must 表示推测时，只能用于
3、肯定句。must do 对一般时的肯定推测must have done 对过去发生的事情作出的肯定判断must be doing 对现在的动作进行肯定推测他们买了一辆新车。他们一定很有钱。They have bought a new car.They must have a lot of money.他现在一定在看小说。He must be reading novels now.路是湿的。昨天晚上一定下雨了。The road is wet.It must have rained last night.can/could(1)表示能力Can you speak Japanese?(2)表示允许(
4、许可或请求许可）You can go now,but he cant.(3)表惊异、怀疑等How can you be so rude?could可表示能力或可能性，多用于过去，也可指现在，通常表示虚拟或作为can的委婉形式。4.can/could 表示推测时，只能用在否定句或疑问句中。Its so late.Can Tom be reading?这个人不可能是玛丽，她生病了。这么晚了，汤姆还在看书吗？It cant be Mary.She has fallen ill.can/could have done表对过去发生行为的可能性进行推测“本可以，本来可能已经”用于肯定句中刚才我还看见他了，
5、所以他不可能出国的。I saw him just now so he couldnt have gone abroad.你本来可以考的更好。You could have had a better mark.5.He cant have been to that town.他不可能去过那个城may/might(1)表示可能性，might比may可能性更小。It may be true.He might not come today.(2)表示请求、许可，多用于肯定和疑问句中May I ask you a question?(3)表示愿望May you be happy all your life
6、.might 比 may 语气更委婉may/might表示推测时，表示对现在或将来要发生的事情把握不大。might/may have done表示对过去发生的动作进行的可能性推测。He may have gone to the clinic.他可能去医务室了。He might have read about the news in the newspaper.他可能已经从报纸上知道这个消息了。may/might表示推测时，只能用于陈述句，表示对现在或将来要发生的动作把握不大。她们明天可能会到这里来。They may come here tomorrow.might 可用于指 过去的行为或者表示
7、可能性更小。我问他我是否可以离开。I asked him if I might leave.（表过去）I asked him“May I leave now?”他也许在作功课吧。He might be doing his homework now.（可能性更小）will/would1.表示意愿，will表示现在的意愿，would表示过去的意愿。Go where you will.She asked if I would go with them.2.表示征求意见或提出请求，主要用于第二人称的疑问句中，will和would均可用，would此时并不表过去，而表示委婉语气。Would Sunday
8、 night suit you?Will/Would you please post the letter for me?3.表示习惯和倾向性will表示现在的习惯，would表示过去的习惯(=used to do)。Oil will float on water.When he was a child,he would often go skiing.4.表示推测will用于谈论现在，would可用于谈论过去，也可用于谈论现在(语气较委婉)。Ask him.He will know.Every family would have some sort of trouble.I thought
9、you would have finished it by now.Will/Would you do?表请求，表意志，愿望，决心would表过去反复发生得动作或某种倾向“总是,总要”used to表过去常常（现在已没有这种习惯）“过去常常”used to 可与状态动词连用 would不可以eg.He used to be a quiet boy.()He would be a quiet boy.()will/wouldIf you will help me with my English,I will be very happy.I promised that I would do my
10、best.You shall do as I say.(命令)1.在陈述句中,shall用于二、三人称表示允诺、警告、命令、决心等。Shall I open the window for you？（征求意见）2.在疑问句中,用于一、三人称，用来表示请求或征求意见。shall,should 和ought toTell him that he shall have the book tomorrow.(允诺)Nothing shall stop me doing it.(决心)Shall he fetch some water for you？（请求）Young people should lea
11、rn how to use computers.3.should常表示劝告、建议、命令，与ought to意义相近，但ought to多表示责任、义务，语气强烈。Every citizen ought to obey law.You ought not to go.You should/ought to have told her the truth earlier.She shouldnt have left without saying a word.4.should/ought to have done表示责备或批评,意为“本应该但”,ought to的语气更强烈,用于否定则表示“本不该
12、但”5.should用于可能性推测时,表“应该，很可能”They left at 5:30.They should get there now.1.Jack described his father,who _ a brave boy many years ago,as a strongwilled man.（2010 安徽卷）A.would be B.would have been C.must be D.must have been 答案：D 解析：句意为“杰克把他的父亲描述为一个意志坚强的人，他的父亲多年前肯定很勇敢”用must have been表示对过去事情的肯定推测。高考真题2.Y
13、ou _ buy a gift,but you can if you want to.（2010 湖南卷）A.must B.mustnt C.have to D.dont have to 答案：D解析：dont have to 意为“没有必要”，符合语境，句意为：“你没有必要买礼物，但如果你想买的话，你也可以买。”3.I have told you the truth._ I keep repeating it?（2010 江西卷）A.Must B.Can C.May D.Will答案：A解析：must 必须,一定 can 可以,能够，may 也许，will 意愿,倾向性动作。前半句说我告诉你
14、事实了,这里用的是现在完成时,表示过去的动作对现在造成了影响,既然我已经说了,我还必须重复一遍吗？4.I_ have watched that movie itll give me horrible dreams.（2010山东卷）A.shouldnt B.neednt C.couldnt D.mustnt答案：A解析：句意应为“我本来不应该看那部电影的-它会使我做噩梦的。”表示“本来不应该做而做了某事”用shouldnt have done,所以A项正确。1.As he had heart attack,he was told that he _ continue the work.A.ne
15、ednt B.may not C.mustnt D.cant2.An Englishman who _ not speak Italian was once traveling in Italy.A.must B.could C.may D.might3.I _ like to make a suggestion.A.could B.would C.must D.might4.I know things are hard with you,but you _ try to get over the difficulties.A.can B.may C.must D.oughtCCBBChoos
16、e the best answers.5.We hope that as many people as possible _ join us for the picnic tomorrow.A.may B.must C.should D.can6.I think Ill give Bob a ring.You _.You havent been in touch with him for ages.A.will B.may C.would D.should7.Could I have a word with you,Mum?Oh dear,if you _.A.can B.must C.may
17、 D.shouldDDB8.It is usually warm in my hometown in March,but it _ be rather cold sometimes.A.must B.can C.should D.would9.You dont have to know the name of the author to find a book.You _ find the book by the title.A.must B.need C.can D.would 10.Although this _ sound like a simple task,great care is
18、 needed.A.must B.may C.shall D.shouldBCB11.You _ be hungry already you had lunch only two hours ago!A.wouldnt B.cant C.mustnt D.neednt12.According to the air traffic rules,you _ switch off your mobile phone before boarding.A.may B.can C.would D.should13.She _ have left school,for her bike is still h
19、ere.A.cant B.wouldnt C.shouldnt D.mustntBDAComplete the following sentences using modal verbs.1.Youve been working all day.You _ be very tired.2.I wonder who that is.It _ be Lisa.Shes in the library at this time.3.It is a long time since we met last time.You _ come and see us more often.4.I havent d
20、ecided where Im going for my holidays.I _ go to Australia.mustcantshouldmay5.My fathers birthday is coming.What _ I get him?6.Why dont you try on this dress?It _ look nice on you.7.-Who was the man talking with your teacher?-Im not sure.It _ be her brother.8.I dont know when the guests be here.They _ arrive at any time.willshallmightwill/could1.Finish the exercises in Discovering Useful Structure.2.Finish exercises in Using Structures in Workbook.Homework
