一.概念

动词的语气有三种:陈述语气,祈使语气和虚拟语气.语气表示说话人对某一行为或事情的看法和态度。

虚拟语气表示动作或状态不是客观存在的的事实，而是说话人的主观愿望、假设或推测等。通常用在两种情况：

1、事后的假设，就是所谓的“事后诸葛亮”

If he had studied hard last term,he would not have failed the exam.要是他上学期努力学习，他就不会考试不及格。

2、与真实情况不符，不可能会发生的情况。

If she were my daughter,I would love her .要是她是我女儿，（事实上她不是我女儿）我会好好爱她。

 

二.最基本的虚拟条件句（用if引导的条件状语从句）

1、虚拟语气的两个特点

if 引导真实条件句

If he has time, he will go with us.

此句是真实条件句，情况可能会发生。

虚拟语气应用的公式就是把原来的条件句过去化，现在变过去，过去变过去完成时。这里可总结出虚拟语气的两个特点：

（1）虚拟语气都是过去的时态，没有现在的时态。

（2）虚拟语气中，从句除了将来虚拟可以用should,都不能用情态动词；主句情态动词必须用过去式。

记住：从句用从句的变化方式，主句用主句的变化方式！

 

 

 

三.虚拟条件句中主句和从句的谓语动词构成

（1）主句和从句与现在事实相反。

If she were my daughter,I would love her .

（2）主句和从句与过去事实相反。

If he had studied hard last term,he would not have failed the exam.

（3）主句和从句与将来事实相反。

If it were Sunday tomorrow,I would go to the park with you.

 

 

 

 

 

 

 

 

 

 

 

 

 

虚拟条件句中主句和从句的谓与动词构成形式如下表

4.混合时间的虚拟语气

如果条件句中的动作和主句的动作不是同时发生，主句和从句的谓语动词的形式应分别根据各自所表示的时间加以调整。

If I had received the passport yesterday, I would start today.

If he had telephoned me last night, I would see him now.

 

四、虚拟语气的其他方式

1、有时even if 或 even though引导的让步状语从句和as if 或 as though引导的方式状语从句也可以用虚拟语气

例：

Even if /even though he were here,I should say it like this.即使他在这里，我也会这么说。

He treats me as if/as though I were his son.他对待我就象我是他儿子。

2、可以用介词短语代替条件状语从句

例：

Whithout air (=if there were no air),there would be no living things.没有空气，就没有生命。

But for your help(if it had not been for your help),I could not have done it so early.要不是有你的帮忙，我不会这么快做完。

3、可以通过上下文或其他方式体现虚拟（此时要注意是主句虚拟，还是从句虚拟）

例：

I was busy that day. Otherwise (=if I had not been busy that day)I would have gone there with you. 那天我很忙。否则的话，我会跟你去的。

I would have finished the work,but I was ill.(=if I had not been ill ,I would have finished the work. )我本来是可以完成工作的，但我病了。

4、省略掉主句或从句的虚拟语气

例：

You could have washed your clothes yourself!你本可自己洗衣服的！

If my grandmother were with me!如果祖母与我在一起该多好！（事实是：祖母已去世。）

If only she had not gone!如果她没走就好了！（事实是：她已走了。）

If only the wind would stop!风要是停了该多好！（事实是：风停的可能性很小。）

 

五、省略掉if 的虚拟语气

在书面语中，如果虚拟条件从句中有were ,had或should ,可以省略掉if,可以把were ,had或should放在句首，构成主谓倒装。

例：

Had you invited us, we would have come to your party.要是你邀请过我们，我们会去你的party.

Were I you, I would do more practice after class.我要是你，我会在班后做更多练习。

Should she lend us a helping hand, we would do so.要是她能帮我们，我们会那么做的。

 

六、wish\would rather后宾语从句中虚拟语气的用法(因为是从句，要用从句的变法)

1)I wish I knew the key to the answer.（现在情况虚拟）

2) I wish that I had gone to the football match last week.（过去情况虚拟）

3) He wishes that we would visit the old school.（将来情况虚拟，注意：此时用would/could）

would rather后宾语从句中虚拟语气的用法:

I'd rather you went home now.我倒宁愿你现在回家。

I would rather you came tomorrow.我倒宁愿你明天来。

I would rather you had stayed at home last night.我倒宁愿你昨天晚上呆在家里。

 

七、虚拟 should +动词原形（should有时可省略）的句型

1、用在表示命令、建议等意义的动词后的宾语从句中

在表示提议、要求、命令、意愿、决定等意义的动词 (如suggest, decide, require, request, demand, propose, insist, order, prefer等)后的宾语从句中，常用 "should+动词原形"，should常被省略。

-The experiment has failed.实验失败了。

 -I suggest you try again. 我建议你再试一次。

 Almost all his friends suggested that he visit Mr. Johnson at once.几乎他所有的朋友都建议他去拜访约翰逊先生。

 Jane's pale face suggested that she was ill, and her parents suggested that she have a medical examination.詹脸色苍白，表明她病了。她父母建议她做一次体格检查。

I insist that a doctor be sent for immediately.我坚持立即请医生。

巧记10个虚拟动词

“一、二、三、四”法。

一个坚持，两个命令，三个建议，四个要求。

一个“坚持(insist)”；两个“命令(order，command)”；三个“建议(suggest, propose, advise)”；四个“要求(demand, require, request, ask)”。

2、主语从句中的应用

 

1）It +be+形容词+主语从句

“It +is +形容词+that引导的主语从句”句型，用动词原形或“should+动词原形”虚拟语气。常用于本句型的形容词有:necessary, important, impossible等；还有与表示提议、要求、命令等动词同源的形容词词，如 desirable(←desire), urgent(←urge), advisable(←advise), preferable(←prefer)等。

It is necessary that he listen to the radio frequently.她很有必要常听收音机。

It is strange that he (should) have so many friends. 真奇怪，他居然有这么多的朋友。

2）It+be+过去分词+主语从句

“It +is +过去分词+that引导的主语从句”，可用“（should） +动词原形”。常用于这一句型的过去分词有：suggested, required, requested, demanded, urged, ordered, proposed, desired, advised, etc.

It is ordered that we (should) go at once. 命令我们立刻出发。

 It has been decided that the meeting (should) be put off. 已决定推迟会议。

3、状语从句中的用法

在for fear that, in order that, so that, lest引导的目的状语从句中，谓语动词一般用should(could, might)+动词原形表达虚拟语气，lest引导得从句用should+动词原形,should 可以省略。

I obeyed her lest she should be angry. 我得顺着她，免得她生气。

Be careful lest you fall from that tree.要当心, 以免从树上摔下来。

In order that she could catch the train, she hurried through her work. 为了赶火车，她匆匆做完了她的工作。

I will not make a noise for fear that I might disturb you.我不会做声的，以免打扰你。

4、表语从句和同位语从句的用法

   在proposal, suggestion, order, requirement, desire, decision, advice, plan, necessity等表示提议、要求、命令等名词的后面的表语从句和同位语从句中，可用“动词原形”或“should +动词原形”虚拟语气。

His suggestion is that the meeting be put off. 他的建议是推迟开会。

He made the suggestion that we go by train. 他建议我们坐火车去。

5、It is time that的虚拟形式

在“It is (high) time + that 从句”结构中，用“did 型”虚拟语气，意为“到了做某事的时间了”。意思是早该干而已经有些晚了，在这种情形下常用过去时。如果是It is time that的虚拟形式，从句也可用“should +动词原形”。

It is(high/about)time that 动词过去式(be多用were)

It is high time that you caught the bus.是你该赶车的时候了。

It is (high) time that you went to school.到了你上学的时间了。

 

总之一句话，不管什么从句，有表示命令、指使、建议的意思，就可用“should +动词原形”虚拟语气。

 

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