情態(tài)動詞知識點(共6頁)

1、一 表能力Can /be able to 表現(xiàn)在的能力； will be able to 表將來的能力；could/was/were able to 表過去的能力如：I am starving to death. I can eat two bowls of rice now.現(xiàn)在的能力If you have a good sleep, you will be able to work out this problem.將來的能力The fire spread through the hotel very quickly but everyone was able to get out.（過去

2、有能力做并且成功地做了某事）I could have worked out the problem, but I didnt .（過去有能力做但未做）單項選擇I should have been there,but I _not find the time.A. would B. could C. might D. shouldIn spite of many difficulties, he _save the boy from the ruins.A. had to B. would C. could D. was able to 二表推測（可能性）1.可能性可分為客觀的可能性和具體事情實

3、際發(fā)生的可能性兩種。所謂客觀的（理論的）可能性即不涉及具體某事是否發(fā)生，此種用法常常可以說明人或事物的特征。情態(tài)動詞can 可用于肯定句中表示客觀的（理論的）可能性，而表示具體事情實際發(fā)生的可能性時，can 一般不用于肯定句。如：Accident can happen on such rainy days.客觀的可能性Peter may come with us tonight, but he isnt sure yet.(實際可能性，不用can ) 2.表具體事情實際發(fā)生的可能性：（1）表示具體事情實際發(fā)生的可能性的層次比較（見下表）：詞形肯定式否定式疑問式Must必定，必然/Will很可能

4、，大概不會，不該會-嗎？Would 可能性比will 小語氣比wont弱語氣比will嗎Should說話者有較大的試探性/Ought to 說話者有較大的試探性（含義同should）/Can /不可能有可能嗎？Could 可疑的可能不可能語氣比can 弱May或許，也許，也未可知，也說不定可能不/Might比may 還弱比may not 還弱/ （2）表示具體事情實際發(fā)生的可能性時，may,must 常用于肯定句，一般不用于否定句和疑問句（may not 表示“可能不”）：can 常用于否定句、疑問句或感嘆句中，表示疑惑、驚訝或不相信的意思；could既可用于肯定句又可用于否定句、疑問句中。如

5、：This cant/couldnt be done by him.(表示不相信)This may not be done by him.(表示不確定)He could be on his way home now.(could 不如may/might常用)Can this be done by him？（表示疑惑、驚訝）Mr. Bush is on time for everything. How can it be that he was late for the opening ceremony?(表示疑惑、驚訝)I didnt hear the phone. I must have b

6、een asleep.(表肯定)-Are you coming to Jeffs party?-Im not sure. I might go to the concert instead.(表不確定)題組訓(xùn)練用 can,could, may, might, must填空Sorry,Im late. I _have turned off the alarm clock and gone back to sleep again.That _not be Mary. Shes in hospital.How _you be so stupid?3.would, could, should, mig

7、ht 并不一定與過去時間有關(guān)，而是表示可能性弱于它們相應(yīng)的現(xiàn)在時形式。如：This may/might be done by him.(后者比前者語氣弱)4.should/ought to 表推測時，表示說話者有較大的試探性。 如：He ought to /should be here in time-he started early enough.We should arrive before dark.The roads should be less crowed today.三表請求、允許、允諾1.當(dāng)對方是決策者時，你代表你（們）自己（I ,we）或代表第三者（he ,she, they

8、）向?qū)Ψ?you)請示或提出建議時用：Shall I (we)-?Shall he/she/they-?Would/will you -? 如：Shall we begin our class ?Shall the driver wait outside?When shall my father be able to leave hospital?Would you do me a favor?2.could/might/would/should 表委婉語氣的功能。 如：-could/might I use your bike tomorrow morning ? -Yes,you can/m

9、ay.(否定：No, Im afraid not)不可說：Yes, you could/might. 回答允許時，用could/might表委婉是不恰當(dāng)?shù)摹Ｈ纾?could I borrow your dictionary?-Yes,of course you can.題組訓(xùn)練單項填空：The room is dirty._we clean it? -of course.A. Will B. Shall C. would D. Do -_he come to see you ? -of course, please. And Id rather he told me the truth.A.

10、Will B。Shall C. Would D. Do 3.當(dāng)你自己（I）是決策者，給對方（you）或第三者（he,she,they）以命令、警告、允諾或威脅時，要用shall 。此外， 當(dāng)宣布法律、規(guī)定時， 也要用shall 。如：You shall leave the room at once, and he also shall.=(I order you and him to leave the room at once.)It has been announced that candidates shall remain in their seats until all the pa

11、pers have been collected.題組訓(xùn)練單項填空：He asked me for this book many times. Please tell him he _have it tomorrow.A.must B. may C. shall D. both B and CIt has been announced that all the students _put on masks()before going to school in case they are infected with SARS virus.A. shall B. will C. need D. m

12、ay四表必要性1.must 常用來表示必要性，意為“必須”。 表示現(xiàn)在或?qū)肀仨氉瞿呈掠谩癿ust+動詞原形”；表示現(xiàn)在或?qū)聿槐刈瞿呈聲r，用 dont have todo sth或dont need to do sth 或neednt do sth；表示過去沒必要做某事時 ，分為以下情況：當(dāng)表示過去沒必要做某事，但事實上卻做了，用neednt have done sth ；當(dāng)表示過去沒必要做某事，而不涉及是否已經(jīng)做了，可用didnt have to do sth或didnt need to do sth 或It was not necessary to do sth等。如。You needn

13、t have worked that late last night . It was harmful to your health.-Did you work very late last night?-No,I didnt. I didnt need to work very late.2.should也可以表示必要性，意為“（義務(wù)上）應(yīng)該”。Should表必要性時，在語氣上比must (必須)弱?！皊hould+動詞原形”表示現(xiàn)在或?qū)響?yīng)該做某事（的必要性）；“should+have +過去分詞”表示過去本應(yīng)該做某事（的必要性）如：I should go and visit him th

14、is afternoon, but I wonder if I will be free.（表示將來的必要性）You should have come to the conference yesterday. What was the reason for your absence?（表示過去的必要性） 題組訓(xùn)練完成下列句子You _(沒必要告訴)her the news for I had told her about it earlier.I _(沒必要非得出去)but I wanted a breath of fresh air.We _(本該買)a new lock for the f

15、ront door.五 表示“寧愿做某事”時，可使用下面這些句式 Would rather do sthWould rather do sth than do sth Would do sth rather than do sthWould rather sb did sthPrefer to do sth Prefer to do sth rather than do sth Prefer doing sth to doing sth 六情態(tài)動詞+have done用法一覽表情態(tài)動詞+完成時意義例句Must have done“想必/準(zhǔn)是/一定做了某事”，否定式為cant/couldnt h

16、ave done It must have rained last night,for the road was quite muddy.The lights were out. They must have been asleep.Can/could have done本來能夠 過去可能會You could have come 5 minutes earlier.Can he have gone to his aunts?Can/could not have done過去不可能 過去沒能I saw Mr.Wang just now.he couldnt have gone to Beijin

17、g.May/might have done“也許/或許已經(jīng)-”一般只用于肯定句和否定句中（在否定句中表示“可能不”），不用于疑問句。用might則表示語氣更加不肯定。Its too late. I think he may have gone to bed.He may not have finished the work.She might have caught a cold.Should/ought to have done“本該做某事，而實際上未做”You should have come to the meeting earlier.You ought to have done th

18、is exercise more carefully.Shouldnt/ought not to have done“本不該做而做了某事”You shouldnt have told her the truth.Neednt have done表示“做了本來不必去做的事”注意：didnt need to do 表示“沒必要做而實際上也沒有做某事”。You neednt have taken a taxi here,for it was very near to my house.I didnt need to clean the windows. My brother did it.Had b

19、etter have done用于事后的建議，含輕微責(zé)備的口吻，意為“要是當(dāng)時做了某事就好了”，其否定式had better not have done 表達(dá)相反的含義。You had better have started earlier.You had better not have scolded her.Would rather have done 表示 “寧愿當(dāng)時做某事”，其否定式 would rather not have done 表達(dá)相反的含義，兩者都表示“后悔”之意。I would rather have taken his advice.I raised objection

20、s at the meeting,but now I would rather not have done that.Would like/love to have done表示過去愿意做某事，但未做成。I would love to have gone to the party last night but I had to work extra hours to finish a report. 題組訓(xùn)練單項填空：I stayed at a hotel while in New York. -Oh,did you ? You _with Barbara.A. could have stay

21、ed B. could stay C. would stay D. must have stayed.I was really anxious about you. You should _home without a word.A. mustnt leave B. shouldnt have left C. couldnt have left D. neednt leaveHe hesitated for moment before kicking the ball, otherwise he _a goal.A. had scored B. scored C. would score D。

22、 would have scored七情態(tài)動詞其他用法要點1.cannot but do sth 不得不，只好 如：I cannot but choose to go.2. may well 和 may as well 結(jié)構(gòu)（） “may well+ 動詞原形 是一種常用結(jié)構(gòu)，意為“完全能，很可能”，相當(dāng)于 to be very likely to .如：He may well be proud of his son.Her appearance has changed so much that you may well not recognize. （2） “may/might as wel

23、l+動詞原形”意為“最好，滿可以，倒不如”，相當(dāng)于had better或to have no strong reason not to. 如 ： You may as well do it at once.We may as well stay where we are.3.Can not （或never）等否定詞與enough 連用表示“再也不為過”。 4.may可以用于祈使句，表示祝愿。如：May we never forget each other.May you return in safely.5.why/how+should 結(jié)構(gòu)表示說話人對某事不能理解、感到意外、驚異等意思，譯為

24、“竟會”如：Why should you be so late today?How should I know?【題組訓(xùn)練】翻譯下列句子：我不得不佩服你的勇氣。（cannot but）她很可能拒絕和你談話。（may well）你最好留在這里過夜。（may as well）祝您的生活美滿、幸福。（may）祝您成功?。╩ay）我真的不明白你憑什么認(rèn)為這件事是我干的。（should）6.must 表示“偏要、硬要”做某事。如：-how old are you, madam?-If you must know, Im twice my sons age.7.may 作“可以”講時，其否定式常用“mustnt”表示“被禁止”；must作“必須”講時，其否定式是“neednt”,表示“不必”如：May I use you car?No,you mustnt.(