英语动词有三种语气：陈述语气、祈使语气、虚拟语气（用来表示说的话不是事实，或者是不太可能发生的情况，而是一种愿望，建议，假设的语气叫虚拟语气。）
虚拟语气的考点：
1.条件句中的虚拟语气的用法； 2.条件句中虚拟语气的倒装； 3.名词性从句中虚拟语气的用法； 4.几种特殊结构中虚拟语气的用法； 5.虚拟语气时态的判定。
一、If引导的虚拟条件句 区别：
If it rains tomorrow，the crops will be saved. 陈述语气 If it rained tomorrow，the crops would be saved. 虚拟语气
真实条件状语从句与非真实条件状语从句 真：eg . If he doesn’t hurry up, he will miss the bus.
如果他不快点，他将错过巴士。( 真实条件状语)（不是虚拟语气） If he is free, he will ask me to tell stories.
如果他是空闲的，他会要求我讲故事。（真实条件状语）（不是虚拟语气）
非真：eg. If I were you, I would go at once.
如果我是你，我马上就会去。 （非真实条件状语从句）
二、虚拟语气在条件从句中：
【例句】1.If you had come a few minutes earlier，you would have met him. 要是你早来几分钟的话，你就能见到他了。（与过去事实相反）
2.If it were sunny tomorrow，i would come to see you. 明天要是天气好的话，我来看你。（与将来事实可能相反） 3.If i were you，i would go at once.
假如我是你的话，我会马上走。（与现在事实相反，事实上我不可能是你）
主从句的谓语形式
时间 现在 过去 If从句的谓语形式 did/were had done 1.did/were 将来 2.should do 3.were to do （一）与现在事实相反的虚拟条件句 表示与现在事实相反的情况，
例1.If I were you, I would take an umbrella.
如果我是你，我会带把伞。（事实：我不可能是你） 2.If I knew his telephone number, I would tell you.
如果我知道他的电话号码，我就会告诉你。（事实：不知道） 3.If there were no air or water, there would be no living things on the earth. 如果没有水和空气，地球上就不会有生物。(事实：地球上既有空气也有水) 4.If I had any money with me, I could lend you some. 如果我带钱了，我就会借给你些。（事实：没带钱） 5.If he studied harder, he might pass the exam.
如果他再努力些，就能通过考试了。（事实：没有努力
Would/could/should/might+V.（原） 主句的谓语形式 Would/could/should/might+V.（原原 Would/could/should/might+have+p.p If+主+did（were），主+would/should/could/might+动词原形
（二）与过去事实相反的虚拟条件句
例：1. If I had got there earlier, I should/could have met her. 如果我早到那儿，我就会见到她。（事实：去晚了）
2.If he had taken my advice, he would not have made such a mistake.
如果他听我的劝告的话，就不会犯这样的错误了。（事实：没有听我的话）
If+主+had done sth，主+would/should/could/might+动词完成式（have done）
（三）表示对将来情况的主观推测
例： 1.If he should come here tomorrow, I should/would talk to him. 如果他哪天来这儿的话，我就跟他谈谈。 （事实：来的可能性很小） 2.If there were a heavy snow next Sunday, we would not go skating. 如果下周日下大雪，我们就不能去滑冰了。（事实：不知能否下雪）
3.If she were to be there next Monday, I would tell her about the matter. 如果她下周一来这儿的话，我就会告诉她这件事的始末。
If+主+did（were to/should do），主+would/should/could/might+动词原形 （在表示建议、命令、要求等含义的宾语从句，谓语动词常用虚拟语气，\"should＋动词原形\"构成，should 可省略。）
（四）有时，主句和条件状语从句的谓语动作若不是同时发生时，虚拟语气的形式应作相应的调整
①从句的动作与过去事实相反，而主句的动作与现在或现在正在发生的事实不符。如： If I had worked hard at school, I would be an engineer, too. 如果我在学校学习刻苦的话，我现在也会成为一个工程师了 If they had informed us, we would not come here now. 如果他们通知过我们的话，我们现在就不会来这里了。
②从句的动作与现在事实相反，而主句的动作与过去事实不符。 如：If he were free today, we would have sent him to Beijing. 如果他今天有空的话，我们会已经派他去北京了。I f he knew her, he would have greeted her. 要是他认识她的话，他肯定会去问候她了。
③从句的动作与过去发生的情况相反，而主句的动作与现在正在发生的情况相反。如： If it had not been raining too much, the crops would be growing much better. 如果天不下太多的雨的话，庄稼会长得更好。
If he had been working hard, he would be working in the office now. 要是他一直努力工作的话，他现在已进了办公室了。
（五）if虚拟句的倒装
当虚拟条件句的谓语动词含有were, should, had时，if可以省略，这时条件从句要用倒装语序，即将were, should, had等词置于句首，这种多用于书面语。如： Should he agree to go there, we would send him there. 要是他答应去的话，我们就派他去。 Were she here, she would agree with us. 如果她在这儿的话，她会同意我们的。
Had he learnt about computers, we would have hired him to work here. 如果她懂一些电脑知识的话，我们已经聘用他来这里工作了。
如果条件状语中有were，had，should时，可以倒装成：were/should/had+主+其他
If i were you，i would try it again. 如果我是你，我会再试一次。 Were i you,…
If he had been there yesterday，he would have seen the film. Had he been there yesterday,… If it should snow tomorrow,we wouldn’t go out. Should it snow tomorrow,…
（六）非真实条件句中的条件从句有时不表达出来，只暗含在副词、介词短语、上下文或其他方式表示出来，这种句子叫做含蓄条件句，在多数情况下，条件会暗含在短语中，如without„., but for„.等
But for his help, we would be working now. 要不是他的帮助，我们还会在工作呢。 Without your instruction, I would not have made such great progress. 要是没有你的指导，我不会取得如此大的进步。
We didn’t know his telephone number; otherwise we would have telephoned him. 我 们不知道他的电话号码，否则我们就会给他打电话。
（七）有时，虚拟条件句中，主、从句可以省略其中的一个，来表示说话人的一种强烈的感情。
①省略从句 He would have finished it. 他本该完成了。 You could have passed this exam. 你应该能通过这次考试了。 ②省略主句 If I were at home now. 要是我现在在家里该多好啊。 If only I had got it. 要是我得到它了该多好啊。
因篇幅问题不能全部显示，请点此查看更多更全内容