4.虚拟语气条件句的倒装

含有虚拟语气的条件状语从句中，如有had，should，were或could，在正式或书面语言中可将if省略，再将句子的主语和谓语动词实行全部倒装或部分倒装。(参阅倒装句)

Had they time(=If they had time)，they would certainly come and help us．他们要是有时间的话，肯定会过来帮忙的。

Should they attack us，we'll wipe them out completely．

如果他们来侵犯，我们就把他们消灭光。

Should it be fine(=If it should be fine)，we would go for an outing．

如果天气好的话，我们就去郊游。

Were I you(=If I were you)，I would go．

我要是你的话，我会去的。

Had I set off a little earlier，I would have caught the train．

我要是早一点点出发的话，就会赶上火车了。

Could the dead man have spoken，he would have identified his murderer．

如果死人会说话，他会认出谁是谋害他的人。