虛擬語氣
概念
虛擬語氣用來表示說話人的主觀愿望或假想,而不表示客觀存在的事實(shí),所說的是一個(gè)條件,不一定是事實(shí),或與事實(shí)相反.虛擬語氣通過謂語動(dòng)詞的特殊形式來表示.英語中的語氣分為陳述語氣、祈使語氣、虛擬語氣三類.
應(yīng)用條件
　　在表示虛假的、與事實(shí)相反的或難以實(shí)現(xiàn)的情況時(shí)用虛擬語氣,表示主觀愿望或某種強(qiáng)烈情感時(shí),也用虛擬語氣.即當(dāng)一個(gè)人說話時(shí)欲強(qiáng)調(diào)其所說的話是基于自己的主觀想法,而不是根據(jù)客觀實(shí)際,就用虛擬語氣.
在非真實(shí)條件狀語從句中的用法
真實(shí)條件狀語從句與非真實(shí)條件狀語從句
條件句可分為兩類,一類為真實(shí)條件句,一類為非真實(shí)條件句.非真實(shí)條件句表示的是假設(shè)或?qū)嶋H可能性不大的情況,故采用虛擬語氣.　　
例：If he doesn’t hurry up, he will miss the bus. 如果他不快點(diǎn),他將錯(cuò)過巴士.( 真實(shí))　　If he is free, he will ask me to tell stories. 如果他是空閑的,他會(huì)要求我講故事.（真實(shí)）　　If I were you, I would go at once.如果我是你,我馬上就會(huì)去. （非真實(shí),虛擬語氣）　　If there were no air, people would die. 如果沒有空氣,人就會(huì)死亡.（非真實(shí),虛擬語氣）
用法及動(dòng)詞形式

從句主句
與現(xiàn)在事實(shí)相反If+主語+did
（be動(dòng)詞were）主語+should/would/
could/might+do
與過去事實(shí)相反If+主語+had done主語+should/would/
could/might+have done
與將來事實(shí)相反1.If+主語+did
2.If+主語+were to
3.If+主語+should主語+should/would/
could/might+do
例句：
表示與現(xiàn)在事實(shí)相反的情況：　　　例： 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號碼,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了,我就會(huì)借給你些.（事實(shí)：沒帶錢）　　5.If he studied harder, he might pass the exam.　　如果他再努力些,就能通過考試了.（事實(shí)：沒有努力）　　　2、表示與過去事實(shí)相反的情況　　例：1. If I had gotten there earlier, I should/could have met her. 如果我早到那兒,我就會(huì)見到她.　?。ㄊ聦?shí)：去晚了）　　2.If he had taken my advice, he would not have made such a mistake. 如果他聽我的勸告的話,就不會(huì)犯這樣的錯(cuò)誤了.　?。ㄊ聦?shí)：沒有聽我的話）　　
表示對將來情況的主觀推測,與將來事實(shí)相反例：1.If he should come here tomorrow, I should/would talk to him.　　如果他哪天來這兒的話,我就跟他談?wù)? （事實(shí)：來的可能性很小）　　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)：不知能否下雪）　　3.If she were to be there next Monday, I would tell her about the matter.　　如果她下周一來這兒的話,我就會(huì)告訴她這件事的始末.　　
有時(shí),虛擬條件句中,結(jié)果主句和條件從句的謂語動(dòng)作若不是同時(shí)發(fā)生時(shí),虛擬語氣的形式應(yīng)作相應(yīng)的調(diào)整.　　
①從句的動(dòng)作與過去事實(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.　　如：　　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,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.　　如果他們通知過我們的話,我們現(xiàn)在就不會(huì)來這里了.　
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,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)識她的話,他肯定會(huì)去問候她了.　　
當(dāng)虛擬條件句的謂語動(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序,即將were, should, had等詞置于句首,這種多用于書面語.　　如：　　Should he agree to go there, we would send him there.　　要是他答應(yīng)去的話,我們就派他去.　　Were she here, she would agree with us.　　如果她在這兒的話,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的話,我們已經(jīng)聘用他來這里工作了.　　
非真實(shí)條件句中的條件從句有時(shí)不表達(dá)出來,只暗含在副詞、介詞短語、上下文或其他方式表示出來,這種句子叫做含蓄條件句,在多數(shù)情況下,條件會(huì)暗含在短語中,如without…., but for….等
如：　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號碼,否則我們就會(huì)給他打電話.　　
有時(shí),虛擬條件句中,主、從句可以省略其中的一個(gè),來表示說話人的一種強(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. 你應(yīng)該能通過這次考試了.　　
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. 要是我得到它了該多好啊.、
虛擬語氣的其他用法
用在wish 后的賓語從句
a、表示與現(xiàn)在事實(shí)相反的愿望,謂語動(dòng)詞用過去式　　
eg.I wish I had your brains.　　我希望我有你那樣的頭腦.(事實(shí)：我根本比不上你)　　
b、表示與過去事實(shí)相反的愿望,謂語動(dòng)詞：had+done　　
eg:I wish I had known the truth of the matter.　　我希望我原來知道這件事的真相.（事實(shí)：原來不知道）　　
c、表示將來難以實(shí)現(xiàn)的愿望,謂語動(dòng)詞：should/would + 動(dòng)詞原形
eg.I wish I should have a chance again.　　我希望我還能有一次這樣的機(jī)會(huì).（事實(shí)：很難再有這樣的機(jī)會(huì)了）　　
(注：if only和as if/as though也有相同用法）
用在目的狀語從句中
　　1.在for fear that, in case, lest引導(dǎo)的從句中,若用虛擬語氣時(shí),從句謂語為：should + 動(dòng)詞原形.并且 should不能省略
eg.She examined the door again for fear that a thief should come in.　　她又把門檢查了一遍,以防盜賊的進(jìn)入.　　He started out earlier lest he should be late.　　他很早就出發(fā)了以防遲到.　　
在so that, in order that所引導(dǎo)的目的狀語從句中,從句中的謂語為：can / may / could / might / will / would / should + 動(dòng)詞原形.　　
eg.He goes closer to the speaker so that he can hear him clearer. 他走近說話的人以便能聽得更清楚.　　He read the letter carefully in order that he should not miss a word. 他把信讀得很仔細(xì)以便不漏掉一個(gè)單詞.
其他用法
1、一想要(desire)二寧愿(prefer)三命令(order, command)四建議(advice. Suggest, propose)五要求(demand , require, request , desire , insist)中,無論主句謂語動(dòng)詞為何種時(shí)態(tài),從句的謂語動(dòng)詞都用：“should + 動(dòng)詞原形”或只用“動(dòng)詞原形”.　　如：　　He suggested that we (should) takethe teacher’s advice.　　He insisted that we (should) takethe teacher’s advice.　　He demand that we (should) takethe teacher’s advice.　　He ordered that we (should) takethe teacher’s advice.　　
insist如果翻譯成堅(jiān)持某種動(dòng)作才用虛擬語氣；翻譯成堅(jiān)持某種觀點(diǎn)就不用虛擬語氣.
　　　如：He insist he is a student.　　他堅(jiān)持說他是個(gè)學(xué)生.　　這個(gè)語句表示的是事實(shí),因此在這個(gè)語句中不能使用虛擬語氣.　　
suggest意為“建議”才用虛擬語氣,意為“暗示”則不用虛擬語氣.　　如： 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),因此它就沒有用到虛擬語氣.　　
2、表情緒.觀點(diǎn)的形容詞或名詞也要用虛擬語氣.如:necessary、important、impossible、natural、strange、surprising、funny、right、wrong、better、a pity等.
句型：It is.that +主語從句,從句的謂語動(dòng)詞都要用should+原型 或只用動(dòng)詞原型.　　
在even if, even though 所引導(dǎo)的讓步狀語從句中,可用虛擬語氣,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.如：　　Even if he were here himself, he should not know what to do.　　即使他親自來也不知該怎么辦.（事實(shí)：他沒來）　　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）　　
在whatever,whichever,whenever,whoever, wherever,however, no matter wh-word 等引導(dǎo)的讓步狀語從句中,從句虛擬語氣結(jié)構(gòu)為：　　指現(xiàn)在或?qū)恚?may +動(dòng)詞原形.　　如：　　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.　　不管他來的多么晚,我都會(huì)等他.　　指過去： may +完成式 .　　如：　　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等之后的賓語從句常表示與客觀事實(shí)不相符的一種愿望,故使用虛擬語氣.其虛擬語氣的結(jié)構(gòu)為：　　
過去: had + 過去分詞 ; 現(xiàn)在: 過去時(shí)(be用were ) ; 將來: 過去時(shí)(be用were )　　如：　　I’d rather you had seen the film yesterday.　　我倒想你昨天看過了這場電影.　　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　　
虛擬語氣還可用在定語從句中,表示：“早該做某事了”時(shí),定語從句中的謂語動(dòng)詞須用虛擬語氣,其虛擬語氣的結(jié)構(gòu)為：It is (high / about) time that + 主語+ 動(dòng)詞的過去式/ should + 動(dòng)詞原形,即從句用虛擬過去式.　　如　　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.　　
簡單句中的虛擬語氣　　
說話時(shí),為了表示客氣、謙虛、委婉而有禮貌,言語常使用虛擬語氣.其虛擬語氣的結(jié)構(gòu)形式常為：would / could / might / should + 動(dòng)詞原形.　　如：　　Would you mind my shutting the door?　　我把門關(guān)起來你介意嗎?　　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.　　我應(yīng)該同意你的觀點(diǎn).　　
表示“祝愿”時(shí),常用may + 主語+ 動(dòng)詞原形.　　如：　　May you have a good journey!　　祝你一路順風(fēng).　　May your youth last for ever!　　祝你青春永駐.　　
（3）表示強(qiáng)烈的“愿望”、“祝愿”時(shí),常用動(dòng)詞原形.　　如：　　Long live the Communist Party of China.　　中國共產(chǎn)黨萬歲.　　God bless us.　　上帝保佑.　　
（4） 習(xí)慣表達(dá)中常用的虛擬語氣.
① 提出請求或邀請.如：　　Would you like to have a talk with us this evening?　　今天晚上來跟我們聊天好嗎?　　Could I use your bike now?　　我可以用一下你的單車嗎?　?、?陳述自己的觀點(diǎn)或看法.如：　　I should glad to meet you.　　見到你我會(huì)很高興.　　I would try my best to help you.　　我會(huì)盡力幫助你.　?、厶岢鰟窀婊蚪ㄗh.如：　　You’d better ask your father first.　　你最好先問一問你的父親.　　You should make a full investigation of it first.　　你應(yīng)該先全面調(diào)查一番.　?、?提出問題.如：　　Do you think he could get here on time?　　你認(rèn)為他能按時(shí)來嗎?　　Do you expect he would tell us the truth?　　你期望他會(huì)告訴我們真相嗎?　?、?表示對過去情況的責(zé)備時(shí),常用虛擬語氣.其虛擬語氣的結(jié)構(gòu)為：情態(tài)動(dòng)詞 + have + 過去分詞.　　如：　　You should have got here earlier. 你應(yīng)該早就到這里了.　　You should have returned it to him. 你應(yīng)該把它還給他了.　　
省略的虛擬條件句型
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,即將從句中的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.　　I will go, should it be necessary. 假若有必要,我會(huì)去的.　　Had it not been for the bad weather we would have arrived in 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)置于主語之后,而不能與were, should, had 等縮略成Weren’t, Shouldn’t, Hadn’t而置于句首.　?、?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)來的.(=If I had time…)
省略條件句的主語和其后的動(dòng)詞be
　　若主從句主語一致,且謂語部分包含有動(dòng)詞be,通?？蓪⒅髡Z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…)
省略“it+be”
　　If necessary, I would send more farm-hands to help you.　　如果需要的話我會(huì)派更多的民工去幫你.(=If it was necessary, I would…)
省略整個(gè)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.)
在含蓄條件句中的用法
　(1) 條件暗含在短語中.如：　　We didn’t know his telephone number; otherwise we would have telephoned him.　　我們不知道他的電話號碼,否則我們就會(huì)給他打電話.（暗含條件是otherwise）　　Without your help, we wouldn’t have achieved so much.　　沒有你的幫助,我們不可能取得這么大的成績.　?。ò岛瑮l件是介詞短語without your help）　　But for your help, I would not have succeeded in the experiment.　　如果沒有你的幫助,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）.