虚拟语气(Subjunctive Mood)这一语法项目是各类英语考试中心测试的重点之一。虚拟语气是一种特殊的动词形式，用来表示说话人所说的话并不是事实，而是一种假设、愿望、怀疑或推测。

（⒈） 用if条件从句表示的虚拟条件，是虚拟条件最普通的方式。

① 虚拟现在时表示与现在事实相反的假设，其if从句的谓语形式用动词的过去式(be 一般用were)，主句用would/ should/ could/ might +动词原形，例如：If I were in your position I would marry her.

② 虚拟过去时是表示与过去事实相反的假设，if从句的谓语形式用过去完成时即had+过去分词，主句用would / should / could / might + have +过去分词，例如：If it had not rained so hard yesterday we could have played tennis.

③ 大多数的虚拟条件句属于上面三种情况的一种，但并不排除存在条件和后果中，一个和现在情况相反，另一个和过去情况相反，例如：If you had followed what the doctor said, you would not be so painful now.这个句子在高中出现频率颇高。

④ 但是，如果后果用了虚拟语气，而条件却用陈述语气，这种用法是错的。

（⒉） 除了表示虚假条件外，if从句还可以表示对将来的推测，由于是将来还没有发生的，所以谈不上是真实的还是虚假的，只能说这个事情发生的可能性有多大。一般情况下，可以用陈述语气的if从句来表示对一个未来事实的推测，这个事实是完全可能发生的。If从句的谓语形式用一般过去式或用were to / should +动词原形，主句用would / should /could/ might +动词原形，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月四级第44题）

（⒊ ）有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if 省去，而将had , should, were 等词提到主语之前，即用倒装结构,这时候，如果出现not等否定词，否定词需放在主语后面。这种结构在口语中很少使用，但频频在各类考试中出现，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 ）大多数的虚拟条件通过上面所讲的两种方法表达，但在个别句子中也可以通过介词without和介词短语but for表达，副词otherwise等表达出来。例如：We didn't know his telephone number; otherwise we would have telephoned him.（1995年6月四级第46题）值得注意的是，包含but for的句子，谓语动词必定要用虚拟形式，但包含without等短语的句子，谓语动词未必一定要用虚拟语气。

（⒌ ）有时虚拟条件不是明确地表达出来，而在蕴含在用but引导的从句里，于是便出现了有谓语动词是虚拟语气的主句加上谓语动词是陈述语气的but从句构成的并列复合句，例如I would have hung you but the telephone was out of order.在这样的句子里，如果主句没有用虚拟语气，或者从句用了虚拟语气，都是错的。

（⒈） 在表示愿望的动词wish后的宾语从句中，需用虚拟语气。（wish后的that 常省略），根据主句时态，从句谓语时态相应退后一位，例如：How she wished his family could go with him.

（⒉） 在具有愿望、请求、建议、命令等主观意愿的动词(desire, demand, advise, insist, require, suggest, propose, order, recommend, decide …) 后的宾语从句中需用虚拟语气。谓语动词用(should) +动词原形。值得注意的是，如果宾语从句的动词是否定的，否定词not的位置应在动词之前，而不是动词之后。例如：The head nurse insisted that the patient not be moved.另外，如suggest表达“暗示”，insist表示“坚持某种说法”时，后面的从句不用虚拟语气，例如：Her pale face suggests that she is ill.或He insisted that he did not kill the boy.

除此之外，上述动词也要求用虚拟式：

① 在It is+上述动词的过去分词，其后所跟的主语从句中，如It is suggested that pupils wear school uniforms.

② 在上述动词相应的名词形式作主语+连系动词，其后的表语从句中，例如His suggestion was that classed be re-scheduled.

③ 在对上述动词相应的名词进行解释的同位语从句中，如：The workers raised the demand that their pay be increased to cope with the inflation.

⒊ would （had）rather , would sooner也用来表达主观愿望，它们之后的宾语从句中需用虚拟语气。谓语动词用过去式表示现在或将来，用过去完成式表示与过去事实相反，例如：I would rather he went right now.

（⒈） it is +necessary等形容词后，that主语从句中虚拟形式使用，这类形容词包括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 之后的定语从句中需用虚拟语气。谓语动词用过去式，例如It is high time that you went to school

（⒊）虚拟语气在as if / as though 引导的方式状语从句中的应用（谓语动词形式与wish后的宾语从句基本相同）表示与现在事实相反或对现在情况有怀疑，谓语动词用过去式。例如：He felt as if he alone were responsible for what had happened. 表示过去想象中的动作或情况，谓语动词用过去完成式。

（⒋） 在lest 引导的状语从句中，谓语动词多用虚拟语气，(should )+动词原形。例如： The mad man was put in the soft-padded cell lest he injure himself.（1998年1月四级第38题）

（⒌） 在if only 引起的感叹句中需用虚拟语气。谓语动词用过去式或过去完成式。例如： Look at the terrible situation I am in! if only I had followed your advice.

1.I wish.....(一定用虚拟)

1）I wish i were you

2)I wish that she were here with me

2、as if...../as though 好像 (不一定用虚拟，要看说话的语境``)

1）He speaks as if he were an American.(如果他真的是美国人就不用虚拟了`)

2）He looks as if nothing had happened.

3、if I did/were....I would......

1)If I were you,I wouldn't do that

2)If it were to snow tomorrow,they would not go out

.(用were to 和were的区别是were to 是对将来的虚拟，

用were是对现在的虚拟`详见二、虚拟语态的几种形式```)

4、在suggest that ,advise that,require that等固定搭配后要用虚拟语态！

1、对现在的虚拟：（直接用动词的过去时....）

if I did /were.... I would.......

2、对将来的虚拟：if ..were to..I would....= if ..did...I would....

(此项与对现在的虚拟相同，但对现在的虚拟不用were to.

要区别对将来的虚拟和对现在的虚拟``一般句子里面都有时间标志``)

(If it were to rain tomorrow,we would not go out.

=If it rained tomorow,we would not go out.)

3、对过去的虚拟 If I had done....I would have done....

(If I had known the answer, I would have told you.)

(至于If ..had been done...would have done

前面的been只是因为是被动语态```所以要看句子的具体意思````)

固定句型的补充。

要用虚拟语态的句子:

I would rather I could......(I would rather she could not come here)

if only..(但愿....)

A:I will go to Korea next month.B:If only I could go with you

虚拟语态表示动作或状态不是客观存在的事实，而是说话人的主观愿望，假设，推测，命令，建议，要求等。

（1）. 与现在事实相反的假设：一般过去时（be用were)，主句结构{ should(would)等+动词原型}

例如：If they were here ,they would help you.如果他们在这，会帮助你的。

（2）. 与过去事实相反的假设：过去完成时主句结构：{should(would)等+have+过去分词}

例如：If he had come yesterday,i should(would)have told him about it.如果他昨天来的话，我会把这件事告诉他的。

（3）. 表示对将来不大发生的事的假想。一般过去时，were+不定式，should+动词原形；主句结构：{should(would)+动词原形。

例如：If you succeeded ,everything would be all right.如果你将来成功了一切都会好的。