英语的动词一般可带有三种不同的语气：陈述语气，祈使语气和虚拟语气。不同的语气用动词的不同形式（或句法形式）来表示。 一、 虚拟条件句
条件句有两类：一类是真实条件句，一类是虚拟条件句
如果假设的情况是有可能发生的，就是真实条件句，谓语用陈述语气。
If you don’t work hard, you will fail.如果你不努力，就会失败。
If it is fine tomorrow, we will go for a picnic.如果明天天气好，我们就去野餐。
如果假设的情况过去、现在、将来都不存在，或者可能性极小，则为虚拟语气
| 条件从句的谓语动词形式 | 主句谓语动词形式 |
与过去事实相反的假设 | had done | would/could/might/should have done |
与现在事实相反的假设 | 过去时(was→were) | would/could/might/should do |
与将来事实相反的假设 | 过去时 (was→were ) ; should do; were to do布鞋套 | would/could/might/should do |
| | |
1.与现在事实相反的虚拟
What would you do if you won the lottery?假如你中了，你会做什么？
If I were you, I would seize the chance to go abroad. 如果我是你，我会抓住这次出国的机会。
If I had a lot of money now, I would travel around the world.假如我现在有很多钱，我会环游世界，
2.与过去事实相反的虚拟
If you had been here yesterday, you would have seen her.如果昨天你在这里，就会见到她了。
If he had driven more carefully, he would not have had the car accident yesterday.如果他小心驾驶的话，昨天就不会出事故了。
3. 与将来事实相反的虚拟
If it were to rain/should rain/rained tomorrow, our plan would be put off.假如明天下雨，我们的计划才可能推迟。（下雨的可能性很小）
If we were to picnic, we would not be able to help.如果到时候我们去野餐，就没办法帮忙了。（不会去野餐）
二、错综、混合虚拟语气
通常，在上面表格里反映的是非真实条件句的虚拟语气模式，从句和主句的谓语动词时间是一致的，如果两者时间不一致，此时就是混合型虚拟语气。混合型虚拟语气的使用要求“各自为政”，即从句和主句根据各自假设的时间不同，采用上面表格中对应的的谓语动词形式。
1. If I had seen you, I would not be so worried now. (从句是对过去的假设，主句是对现在的假设)
2. If you had not watched television so late last night, you would not be so sleepy now.( 从句是对过去的假设，主句是对现在的假设)
3. Had you followed the doctor’s suggestion, you would be fine now.( 从句是对过去的假设，主句是对现在的假设)
4. If I had made some money last summer, I would go on holiday next month.( 从句是对过去的假设，主句是对将来的假设)
5. You didn’t let me drive. If we had driven in turns, you wouldn’折叠浴巾架t be so tired now. (从句是对过去的假设，主句是对现在的假设)废气焚烧
6. If I were your mother, I would let you go out this weekend. (从句是对现在的假设，主句是对将来的假设)
三、含蓄虚拟语气
虚拟语气中的“含蓄之美”指的是含蓄虚拟语气。因为有时假设的情况并不是以if引导的条件从句形式出现，而是通过一些短语等形式暗示虚拟语气的存在，常用的词语有with, without, but for, otherwise, or，even, in case of, what if(如果…将如何)等等，这种句子往往有主句而无从句 (考试时多数情况是对过去的假设)。
But for your encouragement, I would not have been admitted to this university. 没有你的鼓励，我不可能考上这所大学。（过去）
火油草
Without water, all lives would die. 没有了水，所有生物都会死。（现在）
He felt too tired yesterday, or he would have attended my party. 他昨天太累，否则就能来参加我的派对了。（过去）
I was having a meeting, otherwise I would have come to see you off. 我当时在开会，否则一定会去送你。（过去）
动力钳四、虚名词性从句的虚拟语气
含有should +V的用法，这一部分主要是有关建议和命令的相关从句，包括主语从句，宾语从句，表语从句，同位语从句以及与之相关的形式主语宾语之类的从句。记忆口诀：一个坚持(insist)，两个命令(order, command)，三个建议(suggest, advise, recommend)，四个要求(ask, require, demand, request)。 1. 宾语从句的虚拟语气
He insisted that the meeting be put off.
The general ordered (that) all the soldiers (should ) leave.
He gives orders that the soldiers (should) leave.
2. 表语从句的虚拟语气
My suggestion is that we (should) stay here for a rest.
3. 同位语从句的虚拟语气
There is no suggestion that she (should) resign.
4. 主语从句的虚拟语气主要体现在It做形式主语的三种情况： It’s +p.p +that ； It’s + adj. +that； It’s + n. +that
常用的动词recommand, demand, desire, order, request, require, suggest,command
常用的形容词important, necessary, right, advisable, natural, strange, surprising, reg
retful,urgent, vital, insistent, essential
常用的名词duty, pity, no surpise, no wonder, shame, regret
其实这些词在句子中其实也有建议命令类似的的意思
It’s important that you should take the medicine.
It’s a pity that you should refuse the invitation.
It’s essential that we should learn some knowledge about fist aid.
It’准入控制系统s demanded that all the students should go to the playground.
It was suggested that he should join the club activities.
5. It为形式宾语的情况实际上是上面形式主语的一种变形，是以it为形式宾语的复合宾语从句，it后面的宾语补足语多为形容词或名词，常见词就是上面形式主语后面的那些词。
I consider it vital that he (should) think deeply before acting.
We think it necessary that the meeting (should) be put off.
6. 某些词语如suggest, insist 等有双重含义，所以在使用的时候要注意什么时候用虚拟语气，什么时候不用虚拟语气。
Her smile suggested that she was in favor of the plan.(suggest表示“表明、暗示”时不用虚拟语气)
We insisted that what the boy did was wrong.（insist表示对过去发生的事实的坚持时不用虚拟语气）
五．虚拟语气在特殊句式中的运用，主要有两种情况：
I. would rather, It’s time…, for fear that…
would rather在使用时要注意它的不同用法。因为本身would rather可以直接接动词原形，构成would rather do sth. (than do sth.else); 或者would do sth. rather than do sth.else.而虚拟语气的would rather 是这样使用的would rather sb. did(对现在或将来的假设)/ had done(对过去的假设)
