情態(tài)動(dòng)詞與虛擬語(yǔ)氣知識(shí)點(diǎn)講解

1、情態(tài)動(dòng)詞與虛擬語(yǔ)氣I.情態(tài)動(dòng)詞基本用法情態(tài)動(dòng)詞cancouldmaymightmusthave to用 法能力（體力，智力，技能）允許或許可（口語(yǔ)中常用）可能性（表猜測(cè)，用于否定句或疑問(wèn)句中）可以（問(wèn)句中表示請(qǐng)求）可能，或許（表推測(cè)）祝愿（用于倒裝句中）必須，應(yīng)該（表主觀要求）肯定，想必（肯定句中表推測(cè)）只好，不得不（客觀的必須，有時(shí)態(tài)和人稱(chēng)的變化）否定式疑問(wèn)式簡(jiǎn)答式can not / cannot/can tdoCan do?Yes, can.No, can t.couldn t domay not doMay do?Yes, may.No, mustn t/can t.might not

2、doMight do?Yes, mightNo, might not.Yes, must.must not/mustn t do Must do ? to.No, needn t/don thavedon t have to doDo have to doYes, do.?No, don t.ought）ought not to/oughtn tYes, ought.應(yīng)當(dāng)（表示義務(wù)責(zé)任， 口語(yǔ)中多用 shouldto doOught to do?toNo, oughtn t.用于一三人稱(chēng)征求對(duì)方意見(jiàn)、二三人稱(chēng)許Yes, shall.shallshall not/shan t do Shall

3、do?諾、命令、警告、威脅等No, shan t.應(yīng)當(dāng)，應(yīng)該（表義務(wù)責(zé)任）should not/shouldnShtdould do?should本該（含有責(zé)備意味）will意愿，決心請(qǐng)求， 建議，用在問(wèn)句中would 比較委婉woulddare敢（常用于否定句和疑問(wèn)句中）need需要 ,必須（常用于否定句和疑問(wèn)句中）used to過(guò)去常常（現(xiàn)在已不再）will not/won t doWill/Would doYes, will.would not/wouldn?No, won t. t dodare not/daren t doYes, dare.Dare do?No, daren t.n

4、eed not/needn t doYes, must.Need do?No, needn t.used not/usedn t/usen tYes, used.? No, use(d)n t.Used to doto doDid use to do?Yes, did.didn t use to doNo, didn t.精選文庫(kù)II.情態(tài)動(dòng)詞的重點(diǎn)知識(shí)A computer_think for itself; it must be told what to表示能力的情態(tài)動(dòng)詞用can/coulddo.A.can t B.mustn t C.may notD.might not CouldIcal

5、l you by yourfirst name? Yes,表示許可時(shí)用 may/might ,can/could 都可以，you_表示“能A.will B.couldC.may D.might但在問(wèn)句中用 could ?或 might ？以使口氣委力、許可 ”can 或 may，以使回 Johnny,you_play with the knife, you_hurt的 can婉客氣，其回答一定要用和 答口氣明確（ must 表示一定，必須， mustntmayyourself.表示禁止，不許可） 。A.won t/can t B.mustn t/mayC.shouldn t/must D.ca

6、n t/shouldn t在肯定句中 could 不可以用來(lái)表示過(guò)去某一特定場(chǎng)合的能力，而要用 was/were able to 。在肯定句中都可以用來(lái)表示可能。在含義上must 語(yǔ)氣最肯定 ,may 表示的是事實(shí)上的可能性。表示“推斷、判斷”的 can在否定句中只能用can 和 may。所以 cant時(shí)may,must用以代替mustnt，語(yǔ)氣比may 更肯定。中文可以翻譯為不可能。The fire spread through the hotel very quickly buteveryone_get out.A.had toB.wouldC.couldD.was able toPete

7、r_come with us tonight, but he isn t very suyet.A.mustB.mayC.canD.will而 can 表示的是邏輯上的可能性：Mary is in poor health. She can be ill at any times.Michael_be a policeman, for he s much too short.A.needn tB.can t C.shouldD.mayneeddareshall在疑問(wèn)句只能用He may be very busy now.Can he be very busy now?can，不能用 may 和

8、must。Can he be very busy now?He must be very busy now.need 作為情態(tài)動(dòng)詞只有一種形式，只用于否定句和疑問(wèn)句。dare 作為情態(tài)動(dòng)詞用時(shí)有兩種形式：If he dare come,I will kick him out. I don t know whetherdare 和hedared 兩個(gè)詞形，除了可以用于否定句和疑問(wèn)dare say.句外，還可以用于條件從句或表示懷疑的句子中。注意 :He doesn t dare(to)answer the question.（否定句）Does she dare(to)enter the dark

9、 room? （疑問(wèn)句）用于第一人稱(chēng)：征求對(duì)方的意見(jiàn)。What shall we do this evening?You shall fail if you don t work警告harder.用于第二、三人稱(chēng)：警告、命令、允諾、威脅He shall have the book when I finish reading. 允諾等。He shall be punished. 威脅should勸告、建議、命令、應(yīng)該做、道義上的責(zé)任。You should(ought to) go to class right away.-2請(qǐng)求、建議，would 比 will 委婉客氣。表示意志、愿望和決心。精

10、選文庫(kù)I should(ought to) help him because he is in trouble.Would you pass me the book?I will never do that again.They asked us if we would do that againwill/would情態(tài)動(dòng)詞+havedone 的用法would 可表示過(guò)去反復(fù)發(fā)生的動(dòng)作或某種傾向。would 表示估計(jì)或猜想。could+have done ：本可以做而實(shí)際上未能做。cannot+ have done ：表示對(duì)現(xiàn)在或過(guò)去行為的否定推測(cè)。can+主語(yǔ) + have done ：表示

11、對(duì)過(guò)去行為的懷疑或不肯定（用在疑問(wèn)句中） 。might(may)+ have done ：對(duì)過(guò)去發(fā)生的行為不太肯定的推測(cè)。must+ have done ：對(duì)過(guò)去發(fā)生的行為肯定的推測(cè)。其否定式為：cannot have done 。During the vacation he would visit me every week The wound would not heal. （傷口老是不能愈合）It would be about ten when he left home.What would she be doing there?You could have done better, b

12、ut you didn t try your beHe cannot have been to that town.Can he have got the book?He may not have finished the work.If we had taken the other road, we might have arrived earlier.You must have seen the film.You cannot have seen the film.You needn havet watered the flowers,for it is going to rain.nee

13、dn t+ have done：本來(lái)不必要做的而實(shí)際上又做了。should(ought to)+ have done ：本來(lái)應(yīng)該做而實(shí)際上又沒(méi)有做。 其否定形式表示某中行為不該發(fā)生卻發(fā)生了。注意： didn t need to(have to)do：沒(méi)有必要做而實(shí)際上也沒(méi)有做I didn needt to clean the windows.My sister did it 2 hours ago.You should have started earlier, but you didn t.She shouldn t have taken away my measuring tape,for

14、 I worked to use it.注意： He should have finished the workby now .（表推測(cè)）-3精選文庫(kù)虛擬語(yǔ)氣類(lèi)別用法例句與 現(xiàn) 在從句動(dòng)詞：過(guò)去式（be 用 were）事 實(shí) 相主句動(dòng)詞：If he were here, he would help us.反should/would/could/might+doIf 引 導(dǎo)與 過(guò) 去從句動(dòng)詞： had+done的事 實(shí) 相主句動(dòng)詞：If I had been free,I would have visited you.條件從反should/would/could/might+have+done句

15、與 將 來(lái)從句動(dòng)詞：過(guò)去式/should+ 動(dòng)詞原形事 實(shí) 相 /were+to doIf it should rain tomorrow, we would not go camping.反主句動(dòng)詞： should/would/could/might+動(dòng)詞原形省 略 if將虛擬條件從句中的were， had,should 放到主 Should he come ,tell him to ring me up.的 虛 擬 Were I you,I would not do it.語(yǔ)之前，構(gòu)成主謂倒裝條件句H ad I been free,I would have visited you. If

16、he had listened to me, he would not be in troublenow.不同時(shí)間的虛擬：各遵守各的規(guī)則 If he had told me yesterday,I should know what to do混 合 虛now. If I were you, I would have gone to her birthday party.擬 條 件句 He could have passed the exam,but he wasncarefultenough.虛擬與陳述的混合：各遵守各的規(guī)則 You should have come earlier.The b

17、us left a momentago.but for+ 名詞表示虛擬條件含 蓄 虛擬句子或主句中的謂語(yǔ)動(dòng)詞的形式視具體情況而定。這是考查考生應(yīng)變能力的最佳試題。-Butforyourtimelywarning,we_into great trouble.-You know we re friends.A. would getB. must have gotC. would have gotD. can t have got條件句without+ 名詞表示虛擬條件動(dòng)詞不定式表示虛擬條件Without the air to hold some of the sun's heat, the

18、 earth at night would be freezing cold.It would be only partly right to follow in this way.如果用這種方式，僅僅對(duì)了一半?，F(xiàn)在分詞表示虛擬條件Having knownintime,wemighthavepreventedthe-4過(guò)去分詞表示虛擬條件精選文庫(kù)accident.要是及時(shí)得知的話，我們也許能阻止這場(chǎng)事故。Given more attention, the tree could have grown better.如果多留心的話，這樹(shù)本來(lái)可以長(zhǎng)的更好。副詞 otherwise 表示虛擬條件連詞

19、but 連接的句子表示虛擬條件I was too busy at that time.Otherwise,I would have called you.我當(dāng)時(shí)太忙，否則我就給你打電話了。He _fatter but he eats too little .A. would become B. would have become C. must become D. must have become其它狀 語(yǔ) 從句賓 語(yǔ) 從句主 語(yǔ) 從句as if/as though 引導(dǎo)的狀語(yǔ)從句中動(dòng)詞用did 或had done 或 would could might do。注意： as if/as tho

20、ugh 引導(dǎo)的狀語(yǔ)從句中也可以用陳述語(yǔ)氣：當(dāng)說(shuō)話者認(rèn)為所述的是真實(shí)的或極有可能發(fā)生或存在的事實(shí)時(shí)：It sounds as if it is raining 聽(tīng)起來(lái)像是在下雨。 He talks as if he is drunk 從他談話的樣子來(lái)看他是醉了。in order that/so that 引導(dǎo)的狀語(yǔ)從句中動(dòng)詞用 can/could/may/ might/ would 等 +dodemand, suggest, order, insist 后接的從句中動(dòng)詞為 should+dowish 后的從句中分別用過(guò)去式，過(guò)去完成式和 should/would+do 表示與現(xiàn)在，過(guò)去和將來(lái)情況相反在 It is necessary / important / strange thatIt i