虚拟语气

本节导读

虚拟语气用来表示「与事实相反」的假设、愿望或建议，是专升本英语里相对难的一个语法点，每次考试中大约有一两题。好在它的形式有固定规律，只要抓住标志词和时间，就能稳定得分。

学完这一节，你应该能写出非真实条件句在现在、过去、将来三种情况下的形式，会用 wish、as if、would rather 后面的虚拟形式，并认得 suggest、demand 一类词后面的 should 结构。

真实条件句与非真实条件句

先比较两个句子：

英语	说明
If it rains tomorrow, we will stay at home.	真实条件句：明天下雨是有可能的，主句用 will
If I were you, I would take the job.	非真实条件句：我不可能是你，是与事实相反的假设

真实条件句的从句用一般现在时，主句用将来时；非真实条件句则要把时态「往后退一步」。

非真实条件句的三种形式

与什么事实相反	if 从句	主句	例句
现在	过去式（be 一律用 were）	would/could/might + 动词原形	If I had time now, I would help you.
过去	had + 过去分词	would/could/might + have + 过去分词	If he had studied harder, he would have passed the exam.
将来	were to do 或 should do 或过去式	would/could/might + 动词原形	If it should rain tomorrow, we would put off the trip.

从句和主句的时间不一致时，要分别根据各自的时间选择形式。例如：If you had taken my advice, you would be better now.（如果你当初听了我的劝，现在就好了。）从句与过去相反，主句与现在相反。

省略 if 的倒装

虚拟条件句的从句里如果有 were、had、should，可以把 if 省略，把这三个词提到主语前面：

带 if 的写法	倒装的写法
If I were you, I would go.	Were I you, I would go.
If he had known it, he would have told us.	Had he known it, he would have told us.
If it should rain, we would stay at home.	Should it rain, we would stay at home.

倒装以后，否定词 not 要放在主语后面，不与助动词缩写：Had he not been ill, he would have come.

其他需要虚拟语气的场合

场合	虚拟形式	例句
wish 后的宾语从句	与现在相反用过去式，与过去相反用 had done，与将来相反用 would do	I wish I knew the answer. I wish I had gone.
as if、as though	与现在相反用过去式，与过去相反用 had done	He talks as if he knew everything.
would rather + 从句	现在、将来用过去式，过去用 had done	I would rather you went now.
It is (high) time that…	过去式，或 should + 动词原形	It is time that we went home.