情態(tài)動(dòng)詞+have done的用法\x09could+have done：本可以做而實(shí)際上未能做.\x09You could have done better, but you didn’t try your best.
\x09cannot+ have done：表示對(duì)現(xiàn)在或過(guò)去行為的否定推測(cè).\x09He cannot have been to that town.
\x09can+主語(yǔ)+ have done：表示對(duì)過(guò)去行為的懷疑或不肯定（用在疑問(wèn)句中）.\x09Can he have got the book?
\x09might(may)+ have done：對(duì)過(guò)去發(fā)生的行為不太肯定的推測(cè).\x09He may not have finished the work.
If we had taken the other road, we might have arrived earlier.
\x09must+ 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.\x09You must have seen the film.
You cannot have seen the film.
\x09needn’t+ have done：本來(lái)不必要做的而實(shí)際上又做了.\x09You needn’t have watered the flowers,for it is going to rain.
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’t need to clean the windows.My sister did it 2 hours ago.
\x09should(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.\x09You should have started earlier, but you didn’t.
She shouldn’t have taken away my measuring tape,
for I worked to use it.
注意：He should have finished the work by now.（表推測(cè)）
虛擬語(yǔ)氣
類(lèi) 別\x09用 法\x09例 句
If引導(dǎo)的
條件從句\x09與現(xiàn)在事實(shí)相反\x09從句動(dòng)詞：過(guò)去式（be用were）
主句動(dòng)詞：should/would/could/might+do\x09If he were here, he would help us.
\x09與過(guò)去事實(shí)相反\x09從句動(dòng)詞：had+done
主句動(dòng)詞：should/would/could/might+have+done\x09If I had been free,I would have visited you.
\x09與將來(lái)事實(shí)相反\x09從句動(dòng)詞：過(guò)去式/should+動(dòng)詞原形/were+to do
主句動(dòng)詞：should/would/could/might+動(dòng)詞原形\x09If it should rain tomorrow, we would not go camping.
省略if的虛擬條件句\x09將虛擬條件從句中的were,had,should放到主語(yǔ)之前,構(gòu)成主謂倒裝\x09①Should he come ,tell him to ring me up.
②Were I you,I would not do it.
③Had I been free,I would have visited you.
混合虛擬條件句\x09不同時(shí)間的虛擬：各遵守各的規(guī)則\x09①I(mǎi)f he had listened to me, he would not be in trouble now.
②If he had told me yesterday,I should know what to do now.
③If I were you, I would have gone to her birthday party.
\x09虛擬與陳述的混合：各遵守各的規(guī)則\x09①He could have passed the exam,but he wasn’t careful enough.
②You should have come earlier.The bus left a moment ago.
含蓄虛擬
條件句\x09but for+名詞表示虛擬條件\x09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.\x09---But for your timely warning,we ______ into great trouble.
---You know we’re friends.
A. would getB. must have got
C. would have gotD. can’t have got
\x09without+名詞表示虛擬條件\x09\x09Without the air to hold some of the sun's heat, the earth at night would be freezing cold.
\x09動(dòng)詞不定式表示虛擬條件\x09\x09It would be only partly right to follow in this way.
如果用這種方式,僅僅對(duì)了一半.
\x09現(xiàn)在分詞表示虛擬條件\x09\x09Having known in time ,we might have prevented the accident.要是及時(shí)得知的話,我們也許能阻止這場(chǎng)事故.
\x09過(guò)去分詞表示虛擬條件\x09\x09Given 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.
\x09副詞otherwise表示虛擬條件\x09\x09I 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.
\x09連詞but連接的句子表示虛擬條件\x09\x09He _____fatter but he eats too little .
A. would becomeB. would have become
C. must become D. must have become
其它
狀語(yǔ)從句\x09as 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 though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.\x09①與現(xiàn)在事實(shí)相反
He talks as if he knew where she was．
②與過(guò)去事實(shí)相反
He talks about Rome as if he had been there before.
③與將來(lái)事實(shí)相反
He opened his mouth as if he would say something.
\x09in order that/so that引導(dǎo)的狀語(yǔ)從句中動(dòng)詞用can/could/may/ might/ would等+do\x09Turn on the light so that we can see it clearly.
賓語(yǔ)從句\x09demand, suggest, order, insist后接的從句中動(dòng)詞為should+do\x09He suggested that we not change our mind.
\x09wish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\x09I wish I could be a pop singer.
I wish I would have gone to Shanghai last month.
主語(yǔ)從句\x09在It is necessary / important / strange that…
It is suggested / demanded/ ordered / requested that…等從句中,
謂語(yǔ)動(dòng)詞用should+do\x09It is strange that such a person should be our friends.
其它
句型中\(zhòng)x09It is time that…句型中動(dòng)詞用過(guò)去式或should+do\x09It’s high time that we left/should leave.
\x09would rather所接的從句中動(dòng)詞用過(guò)去式或者過(guò)去完成式\x09I would rather you stayed at home now.
\x09If only句型中動(dòng)詞常用過(guò)去式或者過(guò)去完成式,表示強(qiáng)烈的愿望\x09If only our dream had come true!