情態(tài)動詞的用法歸納

1、情態(tài)動詞的用法要點一 can和could情態(tài)動詞用法例句can/could表示能力1“I dont think Mike can type.” “Yes, he can.”2I can speak fluent English now , but I couldnt last year.在肯定句中，表示客觀可能性，并不涉及具體某事會發(fā)生，常用來說明人或事物的特征。要表達具體某事實際發(fā)生的可能性時，不用can，需用may，might。1 As a human being, anyone can make a mistake.2 I may stay at home this weekend.（實

2、際可能性）3 Peter might come to join us.(實際可能性) 表示請求和允許。1 Can we turn the air conditioner on?否定句中表推測“不可能”1He cant be at home.表示驚異、懷疑、不相信等態(tài)度，主要用在否定句、疑問句和感嘆句中。1 Can this be an excuse for not giving them help?2 How can you be so crazy.特別說明：（1） could用來表示請求時，語氣委婉，主要用于疑問句，不能用于肯定句，答語應用can（即：could不能用于現(xiàn)在時態(tài)的簡略答語中）

3、。如：Could I use your dictionary?Yes, you can.(否定回答可用：No, Im afraid not.)(2) can和be able to辨析can(could)和be able to都可以表示能力，意思上沒有區(qū)別。但can只有現(xiàn)在式和過去式，而be able to則有更多的形式。如：Ive always wanted to able to speak fluent English.Those bags look really heavy, are you sure youll be able to carry them on your own?但是，表

4、示在過去某時的某一場合經(jīng)過一番努力，終于做成了某事，通常不用could，而用was/were able to來表示。這時，was/were able to相當于managed to do或succeed in doing。如：After the accident it was a long time before she was able to walk again.The fire was very big, but most people were able to escape from the building.(3) 慣用形式“cannot too”表示“無論怎么也不（過分）”。如：

5、You cannot be too careful.你越小心越好。 慣用形式“cannot but+ 不定式（不帶to）”表示“不得不，只好”。如： I cannot but admire her determination.我不得不欽佩你的決心。 二may和 might情態(tài)動詞用法例句may/might表示允許、許可。否定回答一般用must not/mustnt,表示“禁止、阻止”之意，但也可以用had better not (最好別)或may not（不可以），語氣較為委婉。1 May I come in and wait?2 May I smoke here?No, you mustnt

6、(或No, youd better not.)表示請求、允許時，1 May I borrow your pen?表示可能性的推測，通常用在肯定句和否定句中，含有“或許”“大概”“可能”之意；1 It may rain this afternoon.2 She may not be at home.may用于祈使句表示祝愿1 May you succeed.2 Long may he live! 愿他能持續(xù)住下去。3 May you have many more days as happy as this one.4 May she rest in peace.愿她安息。慣用句式：“may as

7、 well或might(just)as well+動詞原形”意為“最好，滿可以，倒不如”，相當于“had better或there is no reason to do anything else.1 There is nothing to do, so I may as well go to bed.二must和have to情態(tài)動詞用法例句must1.表示“必須，應該”之意，語氣比should，ought to強烈。其否定形式mustnt表示“不準，不應該，禁止”等意1 You must come to school on time.2 You mustnt drive so fast i

8、n the street.在回答帶有must的問句時，否定回答常用neednt或dont have to，表示“不必”，而不用mustnt1Must I come back before ten? Yes，you must.(No, you neednt)2.表示有把握的推測，意為“一定、準是、相必”，只用于肯定句中.1 It must be my mother3.表示固執(zhí)己見，“一定”。2 If you must,I will tell you .have tohave to“必須，不得不”，意義與must相近。但must表示的是說話人的主觀看法，而have to則往往強調(diào)客觀需要。1 Th

9、e film is not interesting. I really must go now.2 I have to go now, because my mother is in hospital.must只有一種形式，即現(xiàn)在式與過去式都是一種形式，而have to則涉及各種人稱、時態(tài)等方面的變化形式。1I had to work hard when I was your age.2I will have to learn how to use a computer.3In order to take the exam, well have to finish the whole book

10、 by the end of this month .兩者的否定意義不同，mustnt表示“禁止，不許”，dont have to表示不必。1 You mustnt go there.2 You dont have to go there.四shall和should情態(tài)動詞用法例句shall用于第一人稱構(gòu)成的疑問句，表示征求對方意見或請求指示1 Shall I open the window?2 Shall we say 6 oclock, then?3 What shall I get for dinner?用于第二、三人稱陳述句中，表示說話人給對方的命令、警告、允諾或威脅。1 Dont w

11、orry, you shall get the answer this afternoon.(允諾)2 He shall be sorry for it one day, I tell you. （警告）3 You shall do as I say. (命令)4 If you children dont do as I tell you, you shall not go to the party. (威脅) should表示勸告或建議，意為“應該”1 You should read his new book.表示推測，用在肯定句中，對現(xiàn)在的情況或可能發(fā)生的事的主觀推測或期待。意為“想必，大

12、概，或許”1 It should be a nice day tomorrow.2 Try phoning Robert, he should be home now.3 He should be around sixty years old.還可以用在if引導的條件句中，表示一件事聽起來可能性很小，但也不是完全不可能，相當于“萬一”的意思。從句謂語用should+動詞原形構(gòu)成，主句都一定用虛擬語氣1 Ask Tom to ring me up if you should see him. (你萬一見到湯姆，請讓他給我打個電話)2 Should I be free tomorrow, Ill

13、come. (萬一我明天有時間，我就過來)3 If things should change suddenly, please let me know. (萬一情況突變，請通知我)用于疑問句或感嘆句中，表示意外、驚異的情緒，意為“竟會”，與why，what，how，who連用，如果是疑問句，則不需要回答。1 Why should anyone want to marry Tony?2 Dont ask me. How should I know?ought to do表示“應該”之意1 You ought to take care of him.2 Ought I go now?Yes, yo

14、u ought to. /No, you oughtnt to.表示推測。注意與must表示推測是的區(qū)別1 He must be home by now. (斷定他已到家)2 He ought to be home by now. (不十分肯定)說明：should與ought to 表示“應該”時的區(qū)別should 表示自己的主觀看法，而ought to的語氣中，含有“按道理應該”之意。若要反映客觀情況或涉及法律義務(wù)和規(guī)定，一般用ought to。如： You should help them with their work. You are his father. You ought to

15、get him to receive good education.五will和would情態(tài)動詞用法例句will/would用于表示意志或意愿。will指現(xiàn)在1 He is the man who will go his own way. (他是個自行其是的人。)表示請求、建議等，1 Will you please take a message for him?2 Would you please tell me your telephone number?表示習慣或傾向，意為“總是，慣于”。will至現(xiàn)在，would指過去。1 Fish will die without water.2 P

16、eople will talk. (人們總會說閑話。)表示推測，意為“很可能，大概”。will表示推測比should把握大，比must把握小。1 These things will happen.2 That will be the messenger ringing.表示功能，意為“能，行”。慣用形式：will do/would do表示“解決問題”、“就行”。1 Either pen will do.用于否定句中，意為“不肯”、“不樂意”1I wont listen to your nonsense.2No matter what I said, he wouldnt listen to

17、me.表示說話時臨時的決定。1. I will open the door.特別說明：would與used to辨析would可用來表示過去反復出現(xiàn)的動作，但不能表示過去存在的狀態(tài)，所以我們不能說：“she would be a quiet girl.”另外，would強調(diào)過去某種特定情況下的活動，是完全過去的事情，同現(xiàn)在沒有聯(lián)系。而used to則著眼于過去和現(xiàn)在的對比，隱含現(xiàn)在已不存在，動作或狀態(tài)都可表示。Would可以表示不規(guī)則的習慣，used to則不可。如： He used to be a naughty boy and cause trouble. I used to get up

18、 at six in the morning. Sometimes she would take a walk in the neighboring woods. In those days, whenever I had difficulties, I would go to Mr. Chen for help.六need和dare情態(tài)動詞用法例句need用于表示“需要，必要”之意。做情態(tài)動詞時，僅用于否定句和疑問句，只有現(xiàn)在時，過去式要用needn't have，疑問式用need+人稱?,否定式用need not(即needn't），1Need we leave soon?

19、 Yes, you must.(No, you needn't)2You needn't have hurried.(=It was not necessary for you to hurry，but you did).你當時不必這么匆忙。做實義動詞時，其變化與一般的實義動詞相同，后接帶to的不定式（need doing = need to be done ）,過去式用needed、did you need?和didn't need,肯定式用needs/needed/need,疑問式用do、does、did提問，否定式要在前面加don't、doesn'

20、t、didn't1. A job like nursing needs patience and understanding.(need+名詞，need understanding=need to be understood,需要被理解)2He needs to see a doctor.(need to do)3Do you still need volunteers to help clean up after the party?(need somebody to do something) 4They didn't need to start so early.(do

21、not need to do)dare用于表示“敢于”之意。做情態(tài)動詞，沒有人稱和數(shù)的變化，主要用于否定句、疑問句和條件狀語從句中1Dare you tell her the truth? Yes, I dare. /No, I darent.3 How dare you accuse me of lying!4 He darent admit this.用作實義動詞時，其變化與一般的實義動詞相同。在肯定句中，dare后接帶to的不定式；否定句中，dare后既可接帶to的不定式，也可接不帶to的不定式。1 Only a few journalists dared to cover the st

22、ory.2 He doesnt dare (to) go there alone.3 Dont you dare (to) touch it?七“情態(tài)動詞+have done”用法情態(tài)動詞+have done用法例句must have done 表示主觀上對過去已經(jīng)發(fā)生的行為進行推測，意為“想必，準是，一定做了某事”1 She must have gone through a lot.2 He must have visited the White House during his stay in the United States.may/might have done表示對過去已發(fā)生行為的

23、推測，意為“也許/或許已經(jīng)（沒有）“。一般用于肯定句或否定句中，不用于疑問句。用might則表示語氣更加不肯定。1 You may have learnt the news.2 He may not have heard his name called.3 Sorry Im late. I might have turned off the alarm clock and gone back to sleep again.canhave donecannot have done表示對過去發(fā)生的行為的懷疑和不肯定，通常用在否定句和疑問句中。（can換成could時語氣委婉）1 Where can she have gone?2 Could he have done such a foolish thing?3 The boy cant have finished reading the book so soon because it is difficult even to an adult.could have done可用于肯定句中，表示“可能已經(jīng)”之意，此外，還可以表示過去能做而沒做的事，有一種對過去為付諸實施的事情的惋惜。1 He could have kille