虛擬語(yǔ)氣主要用來(lái)表示假設(shè)，而非客觀存在的事實(shí)，所陳述的是一個(gè)條件，不一定是事實(shí)，甚至完全與事實(shí)相反。虛擬語(yǔ)氣是由句中的謂語(yǔ)動(dòng)詞的特殊形式表示出來(lái)的。

操作方法

一、虛擬條件句的基本類型(1) 與現(xiàn)在事實(shí)相反：若與現(xiàn)在事實(shí)相反，條件從句的謂語(yǔ)用過(guò)去式(be通常用were)，主句謂語(yǔ)用“should (would, could, might)+動(dòng)詞原形”。如：If we left now, we should arrive in good time. 假如我們現(xiàn)在就走的話，我們就會(huì)及時(shí)到達(dá)。(2) 與過(guò)去事實(shí)相反：若與過(guò)去事實(shí)相反，條件從句的謂語(yǔ)用過(guò)去完成時(shí)(had+過(guò)去分詞)，主句謂語(yǔ)用“should (would, could, might)+have+過(guò)去分詞”。如：If he had been in that train then, he might have been killed in that accident. 如果當(dāng)時(shí)他也在那列火車上，他可能就死于那場(chǎng)車禍了。(3) 與將來(lái)事實(shí)相反：若與將來(lái)事實(shí)相反，條件從句的謂語(yǔ)用過(guò)去式(be通常用were)，主句謂語(yǔ)用“should (would, could, might)+動(dòng)詞原形”。如：If he went，would you go too? 如果他去，你也去嗎？(大概他不會(huì)去)If I asked him，I'm sure he'd help us. 如果我向他提出要求，肯定他會(huì)幫助我們。(不過(guò)我不打算這樣做)

二、錯(cuò)綜時(shí)間虛擬條件句所謂錯(cuò)綜時(shí)間虛擬條件句即條件從句與主句所指時(shí)間不一致，如從句指過(guò)去，而主句即指的是現(xiàn)在或?qū)?lái)，此時(shí)應(yīng)根據(jù)具體的語(yǔ)境情況，結(jié)合上面提到的三種基本類型對(duì)時(shí)態(tài)作相應(yīng)的調(diào)整。如：If you'd listened to me, you wouldn't be in such trouble now. 如果你聽(tīng)了我的話，你現(xiàn)在也不會(huì)有這樣的麻煩了。If you were in better health, we'd have let you go with us. 你要是身體好一點(diǎn)，我們就讓你和我們一道去了。

三、含蓄虛擬條件句所謂含蓄虛擬條件句即指將條件從句隱藏在上下文一定的短語(yǔ)中的一類條件句。如：Anybody else would have believed you. 任何別人都會(huì)相信你的話了。Without your help, I couldn't have achieved all this. 要不是有你幫助，我不會(huì)取得這些成就。I would have written before, but I have been ill. 我本想給你寫(xiě)信的，但我生病了。

四、if it weren't (wasn't) for與if it hadn't been for這是兩個(gè)很常用的虛擬語(yǔ)氣句型，其意為“若不是(有)”“要不是有”，與but for, without同義。如：If it wasn't (weren't) for the children, we wouldn't have anything to talk about. 要不是因?yàn)楹⒆觽?，我們不?huì)有什么可談的。If it hadn't been for the rain, we would have had a good harvest. 要不是有雨，我們本會(huì)獲得一個(gè)大豐收的。If it hadn't been for the doctor's care, I wouldn't have recovered so soon. 要不是醫(yī)生的照顧，我不會(huì)痊愈得這么快。注：一般說(shuō)來(lái)，if it weren’t (wasn't) for 用于談?wù)摤F(xiàn)在的情況，而if it hadn’t been for 用于談?wù)撨^(guò)去的情況。但實(shí)際上if it weren’t (wasn’t) for有時(shí)也可用于談?wù)撨^(guò)去的情況。

五、使用虛擬語(yǔ)氣的特殊句式(1) I wish…句式：要表示與現(xiàn)在事實(shí)相反的愿望，從句謂語(yǔ)一般過(guò)去時(shí)或過(guò)去進(jìn)行時(shí)，表示與過(guò)去相反的愿望，從句謂語(yǔ)用過(guò)去完成時(shí)或would / could+have +過(guò)去分詞，表示將來(lái)沒(méi)有把握或不太可能實(shí)現(xiàn)的愿望，用would (could)＋動(dòng)詞原形。如：I wish I was ten years younger. 我但愿年輕10歲。I wish I could speak your language. 但愿我能講你們國(guó)家的話。I wish I hadn't wasted so much money. 但愿我沒(méi)浪費(fèi)這么多錢。(2) if only…句式：if only 與 I wish一樣，也是表示與事實(shí)相反的愿望的，其后所虛擬語(yǔ)氣的時(shí)態(tài)與 wish后所接時(shí)態(tài)的情況相同。如：If only Tessa was here now. 要是特薩現(xiàn)在在這兒就好了。If only l knew the answer to your question. 我但愿知道你的問(wèn)題的答案。(3) as if / as though…句式：以as if (as though)引導(dǎo)的方式狀語(yǔ)從句或表語(yǔ)從句，有時(shí)用虛擬語(yǔ)氣，若表示與現(xiàn)在事實(shí)相反，謂語(yǔ)動(dòng)詞用一般過(guò)去時(shí)；若表示與過(guò)去事實(shí)相反，用過(guò)去完成時(shí)；表示將來(lái)的可能性不大，用would (might, could)+動(dòng)詞原形。如：I felt as if I was swimming. 我覺(jué)得好像在游泳似的。At that time she acted as if I were her servant. 當(dāng)時(shí)她的舉止好像我是她的仆人。(4) it's time…句式：從句謂語(yǔ)通常用過(guò)去式表示現(xiàn)在或?qū)?lái)，有時(shí)也用過(guò)去進(jìn)行時(shí)或“should+動(dòng)詞原形”(較少見(jiàn)，且should不能省略)，其意為“(早)該干某事了”。如：It's time you washed those trousers. 你該洗洗那條褲子了。I'm getting tired. It's time we went home. 我累了，我們?cè)摶丶伊恕Ｗⅲ簍ime前有時(shí)有about和high修飾：It's high time we left. 我們?cè)缭搫?dòng)身了。(5) would rather…句式：通常用一般過(guò)去時(shí)表示現(xiàn)在或?qū)?lái)的愿望，用過(guò)去完成時(shí)表過(guò)去的愿望。如：I would rather you came tomorrow. 我寧愿你明天來(lái)。I would rather you didn’t mention the price. 我寧愿你別提價(jià)錢。

六、使用虛擬語(yǔ)氣的賓語(yǔ)從句在表示“堅(jiān)持”“命令”“建議”“要求”等后的賓語(yǔ)從句要用虛擬語(yǔ)氣。這些動(dòng)詞主要包括insist, order, command, advise, suggest, propose, demand, require, request, ask等，其虛擬語(yǔ)氣格式為“should+動(dòng)詞原形”，其中的should在美國(guó)英語(yǔ)中可以省略。如：The doctor advised that he change his job. 醫(yī)生勸他換工作。The detective insisted that he should have a look. 警探堅(jiān)持要查看。The seller demanded that payment should be made within five days. 賣方要求5日內(nèi)付款。Her uncle suggested that she (should) get a job in a bank. 她叔叔建議她在銀行里找個(gè)工作。注意：insist后接賓語(yǔ)從句時(shí)，有時(shí)用虛擬語(yǔ)氣，有時(shí)用陳述語(yǔ)氣，其區(qū)別是：若謂語(yǔ)動(dòng)詞所表示的動(dòng)作尚未發(fā)生，或尚未成為事實(shí)，則用虛擬語(yǔ)氣；若謂語(yǔ)動(dòng)詞所表示的動(dòng)作已經(jīng)發(fā)生，或已經(jīng)成為事實(shí)，則要用陳述語(yǔ)氣。比較：She insisted that I (should) stay for supper. 她一定要我留下吃晚飯。He still insisted that he wasn’t there at the time. 他仍然堅(jiān)持說(shuō)他當(dāng)時(shí)不在那兒。與insist相似，suggest后接賓語(yǔ)從句時(shí)，也可用虛擬語(yǔ)氣或陳述語(yǔ)氣，其區(qū)別是：若謂語(yǔ)動(dòng)詞所表示的情況尚未成為事實(shí)，則用虛擬語(yǔ)氣，此時(shí)suggest通常譯為“建議”；若謂語(yǔ)動(dòng)詞所表示的情況為既成事實(shí)，則要用陳述語(yǔ)氣，此時(shí)的suggest通常譯為“表明”“認(rèn)為”。比較：He suggested that we (should) come another day. 他建議們改日再來(lái)。His smile suggested that he was satisfied. 他的微笑表明他是滿意的。

七、使用虛擬語(yǔ)氣的主語(yǔ)從句形容詞important, impossible, necessary等后的主語(yǔ)從句通常用虛擬語(yǔ)氣。如：It's impossible that he (should) marry her. 他同她結(jié)婚是不可能的。It's important that he (should) remember this. 他記住這一點(diǎn)很有必要。注：在It is amazing (strange, surprising, astonishing, a pity, a shame)以及 I am surprised (sorry) 和I regret等結(jié)構(gòu)后的that 從句中有時(shí)也用should，表示說(shuō)話人的驚異、懊悔、失望等情感，常含有“竟然”之意。如：It's strange that he should come so late. 他竟然來(lái)這么遲真是奇怪。這類句子若用陳述語(yǔ)氣，則不帶感色彩，比較下面兩句：I'm surprised that he should feel lonely. 我很驚訝他竟感到孤獨(dú)。She was surprised that I knew all about it. 這事我全知道她感到驚奇。