英語虛擬語氣

虛擬語氣(Subjunctive Mood)這一語法項(xiàng)目是各類英語考試中心測(cè)試的重點(diǎn)之一。虛擬語氣是一種特殊的動(dòng)詞形式，用來表示說話人所說的話并不是事實(shí)，而是一種假設(shè)、愿望、懷疑或推測(cè)。

Ⅰ用以表示虛擬條件的虛擬語氣

⒈ 用if條件從句表示的虛擬條件，是虛擬條件最普通的方式。

① 虛擬現(xiàn)在時(shí)表示與現(xiàn)在事實(shí)相反的假設(shè)，其if 從句的謂語形式用動(dòng)詞的過去式(be 一般用were)，主句用would/ should/ could/ might +動(dòng)詞原形，例如：If I were in your position I would marry her.

② 虛擬過去時(shí)是表示與過去事實(shí)相反的假設(shè)，if 從句的謂語形式用過去完成時(shí)即had+過去分詞，主句用would / should / could / might + have +過去分詞，例如：If it had not rained so hard yesterday we could have played tennis.

③ 大多數(shù)的虛擬條件句屬于上面三種情況的一種，但并不排除存在條件和后果中，一個(gè)和現(xiàn)在情況相反，另一個(gè)和過去情況相反，例如：If you had followed what the doctor said, you would not have been so painful now.這個(gè)句子在高中出現(xiàn)頻率頗高。

④ 但是，如果后果用了虛擬語氣，而條件卻用陳述語氣，這種用法是錯(cuò)的。

⒉ 除了表示虛假條件外，if從句還可以表示對(duì)將來的推測(cè)，由于是將來還沒有發(fā)生的，所以談不上是真實(shí)的還是虛假的，只能說這個(gè)事情發(fā)生的可能性有多大。一般情況下，可以用陳述語氣的if從句來表示對(duì)一個(gè)未來事實(shí)的推測(cè)，這個(gè)事實(shí)是完全可能發(fā)生的。If從句的謂語形式用一般過去式或用were to / should +動(dòng)詞原形，主句用would / should /could/ might +動(dòng)詞原形，例如：Jean doesn't want to work right away because she thinks that if she were to get a job she probably wouldn't be able to see her friends very often.(1996年1月四級(jí)第44題)

⒊ 有時(shí)可以把含有助動(dòng)詞、情態(tài)動(dòng)詞、be或have的虛擬條件句中的連詞if 省去，而將had , should, were 等詞提到主語之前，即用倒裝結(jié)構(gòu),這時(shí)候，如果出現(xiàn)not等否定詞，否定詞需放在主語后面。這種結(jié)構(gòu)在口語中很少使用，但頻頻出現(xiàn)在各類考試中出現(xiàn)，例如：If it had not rained so hard yesterday we could have played tennis.→Had it not rained so hard yesterday, we could have played tennis.

⒋ 大多數(shù)的虛擬條件通過上面所講的兩種方法表達(dá)，但在個(gè)別句子中也可以通過介詞without和介詞短語but for表達(dá)，副詞otherwise等表達(dá)出來。例如：We didn't know his telephone number; otherwise we would have telephoned him.(1995年6月四級(jí)第46題)值得注意的是，包含but for的句子，謂語動(dòng)詞必定要用虛擬形式，但包含without等短語的句子，謂語動(dòng)詞未必一定要用虛擬語氣。

⒌ 有時(shí)虛擬條件不是明確地表達(dá)出來，而在蘊(yùn)含在用but引導(dǎo)的從句里，于是便出現(xiàn)了有謂語動(dòng)詞是虛擬語氣的主句加上謂語動(dòng)詞是陳述語氣的but從句構(gòu)成的并列復(fù)合句，例如I would have hung you but the telephone was out of order.在這樣的句子里，如果主句沒有用虛擬語氣，或者從句用了虛擬語氣，都是錯(cuò)的。

Ⅱ用在賓語從句中的虛擬語氣

⒈ 在表示愿望的動(dòng)詞wish后的賓語從句中，需用虛擬語氣。(wish后的that 常省略)，根據(jù)主句時(shí)態(tài)，從句謂語時(shí)態(tài)相應(yīng)退后一位，例如：How she wished his family could go with him.

⒉ 在具有愿望、請(qǐng)求、建議、命令等主觀意愿的動(dòng)詞(desire, demand, advice, insist, require, suggest, propose, order, recommend, decide …) 后的賓語從句中需用虛擬語氣。謂語動(dòng)詞用(should) +動(dòng)詞原形。值得注意的是，如果賓語從句的動(dòng)詞是否定的，否定詞not的位置應(yīng)在動(dòng)詞之前，而不是動(dòng)詞之后。例如：The head nurse insisted that the patient not be move.另外，如suggest表達(dá)“暗示”，insist表示“堅(jiān)持某種說法”時(shí)，后面的從句不用虛擬語氣，例如：Her pale face suggests that she is ill.或He insisted that he did not kill the boy.

除此之外，上述動(dòng)詞也要求用虛擬式

① 在It is+上述動(dòng)詞的過去分詞，其后所跟的主語從句中，如It is suggested that pupils wear school uniforms.

② 在上述動(dòng)詞相應(yīng)的名詞形式作主語+連系動(dòng)詞，其后的表語從句中，例如His suggestion was that classed be re-scheduled.

③ 在對(duì)上述動(dòng)詞相應(yīng)的名詞進(jìn)行解釋的同位語從句中，如：The workers raised the demand that their pay be increased to cope with the inflation.

⒊ would (had)rather , would sooner也用來表達(dá)主觀愿望，它們之后的賓語從句中需用虛擬語氣。謂語動(dòng)詞用過去式表示現(xiàn)在或?qū)恚眠^去完成式表示與過去事實(shí)相反，例如：I would rather he went right now.

Ⅲ其他形式的虛擬語氣

⒈ it is +necessary等形容詞后，that主語從句中虛擬形式使用，這類形容詞包括necessary, important, essential, imperative, urgent, preferable, vital, advisable等，例如It is necessary that you listen to the teacher carefully.或者It is essential that you be able to pronounce every single word correctly.

⒉ 在It's (high/about) time 之后的定語從句中需用虛擬語氣。謂語動(dòng)詞用過去式，例如It is high time that you went to school

⒊ 虛擬語氣在as if / as though 引導(dǎo)的方式狀語從句中的應(yīng)用(謂語動(dòng)詞形式與wish后的賓語從句基本相同)表示與現(xiàn)在事實(shí)相反或?qū)ΜF(xiàn)在情況有懷疑，謂語動(dòng)詞用過去式。例如：He felt as if he alone were responsible for what had happened. 表示過去想象中的動(dòng)作或情況，謂語動(dòng)詞用過去完成式。

⒋ 在lest 引導(dǎo)的狀語從句中，謂語動(dòng)詞多用虛擬語氣，(should )+ 動(dòng)詞原形。例如： The mad man was put in the soft-padded cell lest he injure himself.(1998年1月四級(jí)第38題)

⒌ 在if only 引起的感嘆句中需用虛擬語氣。謂語動(dòng)詞用過去式或過去完成式。例如： Look at the terrible situation I am in! if only I had followed your advice.