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。
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。

• If he comes, he will bring his guitar.

非真实条件句结构：

情景	条件从句的谓语动词	主句的谓语动词
与现在事实相反	动词过去式（be要用were）	should/would+动词原形
与过去事实相反	had+过去分词	should/would+have+过去分词
与将来事实相反	1. 动词过去式 2. should + 动词原形 3. were to + 动词原形	should/would+动词原形

1. 与现在事实相反的假设：

条件从句	主句
一般过去时（be用were）	should（would）+动词原形

• If they were here, they would help you.
• 其实：They are not here, and they can’t help you.
• 注意：在虚拟语气的从句中，be动词的过去时态一律用”were“，不用was。
  • If I were you, I would go to look for her.
  • If Tom were here, everything would be all right.

1. 与过去事实相反的假设：

条件从句	主句
过去完成时	should（would）+ have+过去分词

• If he had come yesterday, I should / would have told him about it.
• 其实：He did not come yesterday, so I did not tell him about it.

1. 表示对将来不大可能发生的事情的假想：

条件从句	主句
一般过去时 were to +动词原形 should + 动词原形	should（would）+动词原形

• If I saw her tomorrow, I would tell her the secret.
• If I were to see her tomorrow, I would tell her the secret.
• If I should see her tomorrow, I would tell her the secret.
• 其实：I am not likely to see her tomorrow, and she still doesn’t know the secret.

混合虚拟语气和倒装

混合条件句：主句与从句的动作发生在不同的时间，主句从句谓语动词的虚拟语气形式因时间不同而不同。
此时，主从句的虚拟语气表达需要按照各自的时间状态进行选择。

• If you had asked Tom yesterday, you would know what to do now.
• If it had snowed last night, it would be very cold today.

虚拟条件句的倒装：
虚拟条件句的从句部分含有were，should，或had时，可省略if，再把were，should或had移到从句的句首，实行倒装。

• If they were here now, they would help us.
• =Were they here now, they would help us.
• If you had come earlier, you would have met him.
• =Had you come earlier, you would have met him.
• If it should rain, the crops would be saved.
• =Should it rain, the crops would be saved.

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。

• If she were not in Tianjin next week, the team would have a day off.
• =Were she not in Tianjin next week, the team would have a day off.

学而思-虚拟语气

英语中的语气

语气是用来表示讲话人意图或态度的动词形式。英语中主要有三种语气：陈述语气、祈使语气、虚拟语气。

• I can play the piano.（陈述语气）
• Don’t open the window. （祈使语气）
• If I were you, I would try my best to learn English. （虚拟语气）

虚拟语气的定义

虚拟语气用来表示说话人的主观愿望、假设、推测、建议、想象等。

• I wish I were a white cloud.
• If I were you, I’d take an umbrella.
• My mother suggested that we should go at once.

条件句中的虚拟语气

虚拟情况	从句谓语	主句谓语
与现在事实相反	动词过去式（be动词用were）	should/would/could/might + 动词原形
与过去事实相反	had + 过去分词	should/would/could/might + have + 过去分词
与将来事实相反	动词过去式（be动词用were） were+动词不定式 should + 动词原形	should/would/could/might + 动词原形

• You would not have caught a cold if you had put on more clothes.
• If I were you, I would reconsider their advice.
• If you missed the film tonight, you would feel sorry.
• If I should do it, I would do it in a different way.
• If I were to go to the moon one day, I could see it with my own eyes.

虚拟条件句的倒装

虚拟条件句中含有were，had，should，could时，可以省略if，把were，had，should，could放在主语前。

• If it were not for the sun, there would be not life on the earth.
• = Were it not for the sun, there would be no life on the earth.

含wish的虚拟语气

虚拟情况	从句谓语
与过去事实相反	had + 过去分词
与现在事实相反	动词过去式（be动词用were）
与将来事实相反	would/could/might + 动词原形

• I wish I had visited the Great Wall when I was in Beijing.
• I wish I were a bird.
• I wish you would do that again.

表“坚持、建议、要求、命令”的虚拟语气

• 表“坚持、建议、要求、命令”的动词后宾语从句，可以用虚拟语气，此时从句的谓语用“should + 动词原形”，should可省略。
  • She insisted that the seats (should) be booked in advance.
  • I recommend that everyone (should) buy this dictionary.
• 常用的表“坚持、建议、要求、命令”的动词“：insist，order，command，demand，require，request，advise，propose，suggest，recommend。
  • 注意：suggest表示”暗示，认为“时，不用虚拟语气。
  • insist表示”坚持说；坚持认为某种观点、看法“时，不用虚拟语气