虚拟语气:虚拟条件句中的动词的特殊形式

虚拟语气条件句真实条件句虚拟条件句倒装动词原形评论

条件句(Conditional Sentences)
条件句有两种，一种是真实条件句(Sentences of Real Condition)，表示一个可能实现的情况：
I'11 help him if he asks me.
如果他向我提出，我可以帮助他。
If she isn't in，leave her a note．
如果她不在家，她留一个条子。

另一种是虚拟条件句(Sentences of Unreal Condition)，表示一种纯然假想的情况或实现的可能不大的情况，这时动词需用特殊形式，为虚拟语气，虚拟条件句有两种：
1．谈过去的情况，动词为：
had+过去分词 would have+过去分词
If he had asked me, I would have helped him．
如果他向我提出了，我就帮助他。（但他没向我提出)
If she had left five minutes earlier．she would have caught the train
如果她早五分钟动身，她就赶上火车了。（但动身晚了)

2．谈现在或将求情况，动词为：
过去式would+动词型
If I had the money．I would travel round the world
如果我有钱我将作环球旅行。(但我没有钱。)
I would help you if I could．
如果能我是会帮助你的。（但不可能)

动词为be时，多用were这个形式：
If I were you，I would accept the job．
我要是你我会接受这份工作。

有时if可以省略，这时后面要用倒装语：
Had I taken (=If I had taken)your advice，I wouldn't have made that mistake．
如果我听了你的劝告，我就不会犯那个错误了。
Were I in your position，I would stay．
我要是处在你的地位我会留下。