知识点总结
1） 概念 ：虚拟语气用来表示说话人的主观愿望或假想，所说的是一个条件，不一定是事实，或与事实相反。
2） 在条件句中的应用
条件句可分为两类，一类为真实条件句，一类为非真实条件句。非真实条件句表示的是假设的或实际可能性不大的情况，故采用虚拟语气
非真实条件句
1）时态：可以表示过去，现在和将来的情况。它的基本特点是时态退后。
a.同现在事实相反的假设。
句型 ： 条件从句 主句
一般过去时 should( would) +动词原形
If they were here, they would help you.
b.表示于过去事实相反的假设。
句型： 条件从句 主句
过去完成时 should(would) have+ 过去分词
If he had not been ill and missed many classes, he would have made greater progress.
（含义： He was ill and missed many lessons, so he did not make greater progress.）
c.表示对将来的假想
句型：条件从句 主句
一般过去时 would / should + 动词原形
were+ 不定式 would/should + 动词原形
should+ 动词原形 would/should + 动词原形
If you succeeded, everything would be all right.
If you should succeed, everything would be all right.
If you were to succeed, everything would be all right.
混合条件句
主句与从句的动作发生在不同的时间，这时主，从句谓语动词的虚拟语气形式因时间不同而不同，这叫做混合条件句。这时找准时间状语是关键。
If you had asked him yesterday, you would know what to do now.
（从句与过去事实相反，主句与现在事实相反。）
If it had rained last night (过去), it would be very cold today (现在).
虚拟条件句的倒装
虚拟条件句的从句部分如果含有were, should, 或had, 可将if省略，再把were, should或had 移到从句句首，实行倒装。
Were they here now, they could help us.
Had you come earlier, you would have met him
注意：
在虚拟语气的从句中，动词'be'的形式一律用"were"，不用was。
特殊的虚拟语气词：should
1） It is demanded / necessary / a pity + that …(should) +动词原形
It is suggested that we (should) hold a meeting next week.
It is necessary that he (should) come to our meeting tomorrow.
2）在宾语从句中的应用
在表示命令、建议、要求等一类动词后面的从句中。
order, suggest, propose, require, demand, request, insist, command, insist +that (should) do
I suggest that we (should) hold a meeting next week.
3）在表语从句，同位语从句中的应用
在suggestion, proposal, idea, plan, order, advice等名词后面的表语从句、同位语从句中要用虚拟语气，即（should）+动词原形。
My idea is that we (should) get more people to attend the conference.
I make a proposal that we (should) hold a meeting next week.
注意：这时从句意思中隐含“应该”的意思。
wish的用法
1）用于wish后面的从句，表示与事实相反的情况，或表示将来不太可能实现的愿望。其宾语从句的动词形式为：
|
|
真实状况 |
wish后 |
|
从句动作先于主句动词动作 （be的过去式为 were） |
现在时 |
过去时 |
|
从句动作与主句动作同时发生 （had + 过去分词） |
过去时 |
过去完成时 |
|
将来不大可能实现的愿望 |
将来时 |
would/could +动词原形 |
I wish I were as tall as you. He wished he hadn't said that. I wish it would rain tomorrow.
比较if only与only if
only if表示"只有"；if only则表示"如果……就好了"。If only也可用于陈述语气。
I wake up only if the alarm clock rings. 只有闹钟响了，我才会醒。
If only the alarm clock had rung.当时闹钟响了，就好了。
If only he comes early.但愿他早点回来。
It is (high) time that
It is (high) time that 后面的从句谓语动词要用过去式或用should加动词原形，但should不可省略。
It is time that the children went to bed.
It is high time that the children should go to bed.
常见考法
1.虚拟条件句时态的对应考查；
2.省略if的情况；
3.跟suggest,order,demand,insist,propose,commond,require,requesr等词有关的名词性从句中的虚拟情况。
误区提醒
1.混合条件句的主从句时态不会灵活变化；
2.省略if时，句子调整不正确；
3.不会去找意思中的“应该”含义；
4.陷在虚拟中出不来，把真实条件句当成虚拟条件句。
【典型例题】
1） If I had seen the movie, I ______________ you all about it now.
A. would tell B. will tell C. have told D. would have told
解析：错选D。此题考查混合条件句。从句表对过去的虚拟，主句表对现在的虚拟，所以正确答案为A。
2）The volleyball match will be put off if it ___.
A.will rain B. rains C. rained D. is rained
解析：答案B。真实条件句主句为将来时，从句用一般现在时。
3）_____ to do the work, I should do it some other day.
A. If were I B. I were C. Were I D. Was I
解析：答案C. 在虚拟条件状语中如果有were, should, had这三个词，通常将if省略，主语提前, 变成 were, should, had +主语的形式。但要注意，在虚拟条件状语从句中，省略连词的倒装形式的句首不能用动词的缩略形式。如我们可说 Were I not to do., 而不能说 Weren't I to do.
4). My suggestion is that she ________ more exercise, which will do a lot of
good to her.
A. takes B. must take C. take D. took
解析：错选A。本题要表达“我的建议是她（应该）多锻炼，这对她会有很大好处。”符合虚拟的条件，所以正确答案为C。空前面省略了should.
