用來(lái)表示說(shuō)話(huà)人的主觀(guān)愿望或假想，而不表示客觀(guān)存在的事實(shí)，所說(shuō)的是一個(gè)條件，不一定是事實(shí)，或與事實(shí)相反。
虛擬語(yǔ)氣通過(guò)謂語(yǔ)動(dòng)詞的特殊形式來(lái)表示。
初中階段主要學(xué)習(xí)在條件句中的虛擬語(yǔ)氣。
條件句中的虛擬語(yǔ)氣根據(jù)不同的時(shí)間有三種不同的形式。
時(shí)間 | 條件從句 | 主句 | 例句 |
與現(xiàn)在事實(shí)相反 | If+主語(yǔ)+過(guò)去式（系 | would | 見(jiàn)①②句 |
與過(guò)去事實(shí)相反 | If+主語(yǔ)+had+過(guò)去分詞 | Would | 見(jiàn)③④句 |
與將來(lái)事實(shí)相反 | 過(guò)去式 | would | 見(jiàn)⑤⑥句 |
例句：
① If I were rich, I would travel around the world.
② If I won a million dollars, I would give it to charities.
③ If you had taken my advice, you wouldn’t have failed.
④ If I had known that earlier, I wouldn’t have done it.
⑤ If he should go to Tsinghua University, he would make full use of his time.
⑥ If he were to come here, he would tell us about it.
虛擬語(yǔ)氣誤區(qū):
1.混合條件句的主從句時(shí)態(tài)不會(huì)靈活變化；
2.省略if時(shí)，句子調(diào)整不正確；
3.不會(huì)去找意思中的“應(yīng)該”含義；
4.陷在虛擬中出不來(lái)，把真實(shí)條件句當(dāng)成虛擬條件句。
省略虛擬條件:
1.省略連詞if
有時(shí)可將條件從句的連詞if省略，但此時(shí)應(yīng)用倒裝句型，即把從句中的were,should,had 等提到句首：
Were I Tom,I would refuse. 如果我是湯姆，我會(huì)拒絕。
Should it be necessary,I would go. 假若有必要，我會(huì)去的。
Had it not been for the bad weather we would have arrived on time. 若不是天氣壞，我們就準(zhǔn)時(shí)到達(dá)了。
【注】
① 若條件從句為否定句，否定詞not應(yīng)置于主語(yǔ)之后，而不能與were,should,had 等縮略成Weren’t,Shouldn’t,Hadn’t而置于句首。
② 有時(shí)省略if后提前的had不是助動(dòng)詞：
Had I time,I would come. 假若我有時(shí)間，我會(huì)來(lái)的。(=If I had time…)
2.省略主語(yǔ)和動(dòng)詞be
若主從句主語(yǔ)一致，且謂語(yǔ)部分包含有動(dòng)詞be，通�？蓪⒅髡Z(yǔ)和動(dòng)詞be省略：
If repaired earlier,the tractor would not have broken down.
要是早點(diǎn)兒修一下，拖拉機(jī)就不會(huì)拋錨了。(=If it had been repaired earlier…)
3.省略“it+be”
If necessary,I would send more farmhands to help you.
如果需要的話(huà)，我會(huì)派更多的人去幫你。(=If it was necessary,…)
4.省略條件從句
這樣的省略通常需要借助一定的上下文，即省略條件從句后，所剩下的主句的意思在一定的上下文中意思是清楚的：
I might see her personally. It would be better.
我可以親自去看她，這樣好一些。(=If I saw her personally,it would be better.)
含蓄條件句中
(1) 條件暗含在短語(yǔ)中。如：
We didn’t know his telephone number; otherwise we would have telephoned him.
我們不知道他的電話(huà)號(hào)碼，否則我們就會(huì)給他打電話(huà)。（暗含條件是otherwise）
Without your help,we wouldn’t have achieved so much.
沒(méi)有你的幫助，我們不可能取得這么大的成績(jī)。
（暗含條件是介詞短語(yǔ)without your help）
But for your help,I would not have succeeded in the experiment.
如果沒(méi)有你的幫助，我的實(shí)驗(yàn)就不會(huì)成功。（暗含條件是but for your help）
It would cause great trouble not to lubricate the bearing immediately.
不立即潤(rùn)滑軸承就會(huì)引起很大的故障。
（暗含條件是not to lubricate the bearing immediately）
(2) 條件暗含在上下文中。如：
I would not have done it that way.
我是不會(huì)那么做的。（可能暗含if I were you）
I was busy that day. Otherwise I would have come to help you.
我那天很忙。否則我會(huì)來(lái)幫你的。（可能暗含if I hadn’t been so busy.）
You might come to join us in the discussion.
你可以參加我們的討論。（可能暗含if you wanted to）
I would have bought the DVD player.
我是會(huì)買(mǎi)下那臺(tái)影碟機(jī)的。（可能暗含if I had the money）
But for the storm,we should have arrived earlier.
要不是碰到暴雨，我們還會(huì)早些到。（可能暗含if it had not been for the storm）。
條件狀語(yǔ)從句用法及動(dòng)詞形式:
1、表示與現(xiàn)在事實(shí)相反的情況：
從句：If 主語(yǔ)+過(guò)去時(shí)(Be動(dòng)詞用were)
主句：主語(yǔ)+should/would/could/might+do
eg：
1．If I were you,I would take an umbrella.
如果我是你，我會(huì)帶把傘。（事實(shí)：我不可能是你）
2．If I knew his telephone number,I would tell you.
如果我知道他的電話(huà)號(hào)碼，我就會(huì)告訴你。（事實(shí)：不知道）
3．If there were no air or water,there would be no living things on the earth.
如果沒(méi)有水和空氣，地球上就不會(huì)有生物。(事實(shí)：地球上既有空氣也有水)
4．If I had any money with me,I could lend you some.
如果我?guī)уX(qián)了，我就會(huì)借給你些。（事實(shí)：沒(méi)有帶錢(qián)）
5．If he studied harder,he might pass the exam.
如果他再努力些，就能通過(guò)考試了。（事實(shí)：沒(méi)有努力）
6．she looked at me as if I had been a stranger.
她看我的樣子好像我是一個(gè)陌生人。（事實(shí)：我并非陌生人）
2、表示與過(guò)去事實(shí)相反的情況
從句：If 主語(yǔ)+had+done
主句：主語(yǔ)+should/would/could/might+have done
eg：
1．If I had got there earlier,I should/could have met her. 如果我早到那兒，我就會(huì)見(jiàn)到她。（事實(shí)：去晚了）
2．If he had taken my advice,he would not have made such a mistake. 如果他聽(tīng)我的勸告的話(huà)，就不會(huì)犯這樣的錯(cuò)誤了。（事實(shí)：沒(méi)有聽(tīng)我的話(huà)）
3、表示對(duì)將來(lái)情況的主觀(guān)推測(cè)
主句：主語(yǔ)+should+do
從句：
①if+主語(yǔ)+were to do
②if+主語(yǔ)+should/would/could/might+do
③if+主語(yǔ)+did（動(dòng)詞過(guò)去式）/were
eg：
1．If he should come here tomorrow,I would talk to him.
如果他明天來(lái)這兒的話(huà)，我就跟他談?wù)�。（事�?shí)：來(lái)的可能性很�。�
2．If there were a heavy snow next Sunday,we would not go skating.
如果下周日下大雪，我們就不能去滑冰了。（事實(shí)：下雪可能性很�。�
3．If she were to be here next Monday,I would tell her about the matter.
如果她下周一來(lái)這兒的話(huà)，我就會(huì)告訴她這件事的始末。（事實(shí)：來(lái)的可能性很�。�
4、 有時(shí)，虛擬條件句中，結(jié)果主句和條件從句的謂語(yǔ)動(dòng)作若不是同時(shí)發(fā)生時(shí)，虛擬語(yǔ)氣的形式應(yīng)作相應(yīng)的調(diào)整。這種條件句叫錯(cuò)綜條件句。
①?gòu)木涞膭?dòng)作與過(guò)去事實(shí)相反，而主句的動(dòng)作與現(xiàn)在或現(xiàn)在正在發(fā)生的事實(shí)不符。
eg：
If I had worked hard at school,I would be an engineer,too.
如果我在學(xué)校學(xué)習(xí)刻苦的話(huà)，我現(xiàn)在也會(huì)成為一個(gè)工程師了
If they had informed us,we would not come here now.
如果他們通知過(guò)我們的話(huà)，我們現(xiàn)在就不會(huì)來(lái)這里了。
②從句的動(dòng)作與現(xiàn)在事實(shí)相反，而主句的動(dòng)作與過(guò)去事實(shí)不符。如：
If he were free today,we would have sent him to Beijing.
如果他今天有空的話(huà)，我們會(huì)已經(jīng)派他去北京了。
If he knew her,he would have greeted her.
要是他認(rèn)識(shí)她的話(huà)，他肯定會(huì)去問(wèn)候她了。
5、 當(dāng)虛擬條件句的謂語(yǔ)動(dòng)詞含有were,should,had時(shí)，if可以省略，這時(shí)條件從句要用倒裝語(yǔ)序，即把were,should,had等詞置于句首，這種多用于書(shū)面語(yǔ)。eg：
Should he agree to go there,we would send him there.
要是他答應(yīng)去的話(huà)，我們就派他去。
Were she here,she would agree with us.
如果她在這兒的話(huà)，她會(huì)同意我們的。
Had he learnt about computers,we would have hired him to work here.
如果他懂一些電腦知識(shí)的話(huà)，我們已經(jīng)聘用他來(lái)這里工作了。
6、非真實(shí)條件句中的條件從句有時(shí)不表達(dá)出來(lái)，只暗含在副詞、介詞短語(yǔ)、上下文或其他方式表示出來(lái)，這種句子叫做含蓄條件句，在多數(shù)情況下，條件會(huì)暗含在短語(yǔ)中，如without…，but for…等
eg：
But for his help,we would be working now.
要不是他的幫助，我們還會(huì)在工作呢。
Without your instruction,I would not have made such great progress.
要是沒(méi)有你的指導(dǎo)，我不會(huì)取得如此大的進(jìn)步。
We didn't know his telephone number,otherwise we would have telephoned him.
我們不知道他的電話(huà)號(hào)碼，否則我們就會(huì)給他打電話(huà)。
7、有時(shí)，虛擬條件句中，主、從句可以省略其中的一個(gè)，來(lái)表示說(shuō)話(huà)人的一種強(qiáng)烈的感情。
①省略從句
He would have finished it. 他本該完成了。
You could have passed this exam. 你本能通過(guò)這次考試的。
②省略主句
If I were at home now. 要是我現(xiàn)在在家里該多好啊。
If only I had got it. 要是只有我得到它了該多好啊。
8.注意，在虛擬語(yǔ)氣的從句中，動(dòng)詞be的過(guò)去時(shí)態(tài)一律用were，不用was。
eg：If I were you,I would go to look for him.
如果我是你，就會(huì)去找他。
虛擬語(yǔ)氣的其他用法:
1、一想要( desire )
一寧愿( prefer )
一堅(jiān)持( insist )
二命令( order , command )
三建議( advise , suggest , propose/recommend)
四要求( demand , require , request , ask)中，
無(wú)論主句謂語(yǔ)動(dòng)詞為何種時(shí)態(tài)，從句的謂語(yǔ)動(dòng)詞都用："should + do"。should可以省略。
eg：
He suggested that we (should) take the teacher's advice.
He insisted that we (should) take the teacher's advice.
He demand that we (should) take the teacher's advice.
He ordered that we (should) take the teacher's advice.
insist 意為“堅(jiān)持某種動(dòng)作”才用虛擬語(yǔ)氣；意為“堅(jiān)持某種觀(guān)點(diǎn)，某個(gè)事實(shí)”則不用虛擬語(yǔ)氣。eg：
He insists he is a student.
他堅(jiān)持說(shuō)他是個(gè)學(xué)生。
這個(gè)語(yǔ)句表示的是事實(shí)，因此在這個(gè)語(yǔ)句中不能使用虛擬語(yǔ)氣。
suggest意為“建議”才用虛擬語(yǔ)氣，意為“暗示”則不用虛擬語(yǔ)氣。
eg：
His face suggests that he looks worried .
他的表情暗含著他很擔(dān)心。
這個(gè)句子本身是事實(shí)，因此它就沒(méi)有用到虛擬語(yǔ)氣。
2、表情緒、觀(guān)點(diǎn)的形容詞或名詞也要用虛擬語(yǔ)氣。如：
necessary、important、impossible、natural、strange、surprising、funny、right、wrong、better、a pity ,the shame ,no wonder等。
句型：It is.......that +主語(yǔ)從句，從句的謂語(yǔ)動(dòng)詞都要用 should+原型或 只用動(dòng)詞原型。
eg:
Do you think it is necessary that he (should)not be sent to Lingbao.
It is strange that such a person should be our friend.
奇怪的是這樣一個(gè)人會(huì)成為我們的朋友。
注：這一點(diǎn)還沒(méi)有準(zhǔn)確的說(shuō)法，希望善心人能把這點(diǎn)補(bǔ)充完全。
3、 在even if,even though 所引導(dǎo)的讓步狀語(yǔ)從句中用may/might+動(dòng)詞原形，may/might可以省略，表示與現(xiàn)在相反的情況；
從句用過(guò)去完成時(shí)，表示與過(guò)去相反的情況，類(lèi)似的詞有though/even though/whatever/however/so long as; 主句、從句的結(jié)構(gòu)與if所引導(dǎo)的條件從句結(jié)構(gòu)相同。
eg：
Even if he were here himself,he should not know what to do.
即使他親自來(lái)也不知該怎么辦。（事實(shí)：他沒(méi)來(lái)）
Nobody could save him even though Hua Tuo should come here.
即使華佗在世也救不了他。（事實(shí)：華佗不在世）
4、 在whatever，whichever，whenever，whoever,wherever，however,no matter wh-等引導(dǎo)的讓步狀語(yǔ)從句中，從句虛擬語(yǔ)氣結(jié)構(gòu)為：指現(xiàn)在或?qū)?lái)：may +do。
eg：
We will finish it on time no matter what may happen.
不管發(fā)生什么事，我們都要按時(shí)完成。
We will find him wherever he may be.
無(wú)論他在哪里，我們都要找到他。
I will wait for him no matter how late he may come.
不管他來(lái)的多么晚，我都會(huì)等他。
指過(guò)去：may +have done 。
eg：
You mustn't be proud whatever great progress you may have made.
不管你取得了多么大的進(jìn)步，你也不能驕傲。
We must respect him no matter what mistakes he may have made.
不管他犯過(guò)什么錯(cuò)誤，我們必須尊敬他。
5、一般would rather,had rather,would sooner等之后的賓語(yǔ)從句常表示與客觀(guān)事實(shí)不相符的一種愿望，故使用虛擬語(yǔ)氣。其虛擬語(yǔ)氣的結(jié)構(gòu)為：
過(guò)去 had + done
現(xiàn)在 過(guò)去時(shí)(be 用were )
將來(lái) 過(guò)去時(shí)(be 用were ) （would rather 將來(lái)情況用一般過(guò)去時(shí)）
eg：
I'd rather you had seen the film yesterday.
我倒想你昨天看過(guò)了這場(chǎng)電影。
I'd rather you were here now.
我倒想你現(xiàn)在在這兒。
We'd rather you went here tomorrow.
我們倒想你明天去那兒
注：注意would rather，had rather，would sooner的細(xì)微差別，可以百度一下查查。
6、虛擬語(yǔ)氣還可用在定語(yǔ)從句中，表示：“早該做某事了”時(shí)，定語(yǔ)從句中的謂語(yǔ)動(dòng)詞須用虛擬語(yǔ)氣，其虛擬語(yǔ)氣的結(jié)構(gòu)為：
It is (high / about) time that + 主語(yǔ)+ 動(dòng)詞的過(guò)去式/ should + do（優(yōu)先使用動(dòng)詞過(guò)去式） ，即從句用虛擬過(guò)去式。
It is time that I went to pick up my daughter at school.
我該去學(xué)校接我的女兒了。
It is high time you should go to work.
你早該上班了。
7、 簡(jiǎn)單句中的虛擬語(yǔ)氣
（1） 說(shuō)話(huà)時(shí)，為了表示客氣、謙虛、委婉而有禮貌，言語(yǔ)常使用虛擬語(yǔ)氣。其虛擬語(yǔ)氣的結(jié)構(gòu)形式常為：would / could / might / should +do。
eg：
Would you mind me shutting the door?
你介意我把門(mén)關(guān)起來(lái)嗎？
You should always learn this lesson by heart.
你要把這個(gè)教訓(xùn)牢記于心。
I should agree with you.
我本該同意你的觀(guān)點(diǎn)。（委婉的不同意）
（2）表示“祝愿”時(shí)，常用may + 主語(yǔ)+ do。
eg：
May you have a good journey!
祝你一路順風(fēng)。
May your youth last forever!
祝你青春永駐。
（3）表示強(qiáng)烈的“愿望”、“祝愿”時(shí)，常用do。
eg：God bless us. 上帝保佑。
（4）習(xí)慣表達(dá)中常用的虛擬語(yǔ)氣。
① 提出請(qǐng)求或邀請(qǐng)。eg：
Would you like to have a talk with us this evening?
今天晚上來(lái)跟我們聊天好嗎？
Could I use your bike now?
我可以用一下你的單車(chē)嗎？
② 陳述自己的觀(guān)點(diǎn)或看法。eg：
I should be glad to meet you.
見(jiàn)到你我會(huì)很高興。
I would try my best to help you.
我會(huì)盡力幫助你。
③提出勸告或建議。eg：
You'd better ask your father first.
你最好先問(wèn)一問(wèn)你的父親。
You should make a full investigation of it first.
你應(yīng)該先全面調(diào)查一番。
④ 提出問(wèn)題。eg：
Do you think he could get here on time
你認(rèn)為他能按時(shí)來(lái)嗎？
Do you expect he would tell us the truth?
你期望他會(huì)告訴我們真相嗎？
⑤表示對(duì)過(guò)去情況的責(zé)備時(shí)，常用虛擬語(yǔ)氣。其虛擬語(yǔ)氣的結(jié)構(gòu)為：情態(tài)動(dòng)詞 + have done。
eg：
You should have got here earlier. 你早該到這里了。
You should have returned it to him. 你早該把它還給他了。
8、虛擬語(yǔ)氣在方式狀語(yǔ)從句的應(yīng)用。詳見(jiàn)百度百科之方式狀語(yǔ)從句詞條。
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