与过去事实相反的虚拟条件句中，从句的谓语动词为had＋过去分词；主句的谓语动词为would/should/could/might＋have＋过去分词。

　　If anyone had told me three years ago that I would be spending most of my weekends camping, I would have laughed heartily. (2017·全国卷Ⅰ)

　　三年前如果有人告诉我我将大部分周末用来去野营，我会开怀大笑。

　　If you had come earlier, you could have caught the bus.

　　假如你早来一点的话，你就有可能赶上公共汽车了。

　　[名师点津]　(1)在与过去事实相反的虚拟语气中，可以将条件句中的if省略，把助动词had提前。

　　If I had worked hard, I would have surely succeeded.

　　→Had I worked hard, I would have surely succeeded.

　　如果我当时努力学习的话，我肯定会成功。

　　(2)句型"Had it not been for ..."意为"当时要不是......"。

　　Had it not been for your timely help, we would have been lost in the forest.

　　当时要不是您及时的帮助，我们就可能在森林中迷失了方向。

　　[即时演练1]　

　　(1)补全句子

　　①(2017·北京高考改编)If the new safety system had been put to use, the accident would never have happened.

　　如果新的安全系统投入使用，这次事故就不会发生了。

　　②(2015·北京高考改编)If I hadn't seen it with my own eyes, I wouldn't have believed it.

　　如果不是我亲眼看到，我是不会相信的。

　　③(2013·重庆高考改编)-It rained cats and dogs this morning. I'm glad we took an umbrella.

　　-Yeah, we would have got wet all over if we hadn't.

　　--今天早上下了滂沱大雨。很高兴我们带了伞。

　　--是的。要是我们没带的话就全身湿透了。

　　(2)把下面的句子改为倒装句

　　①(2015·江苏高考改编)It might have saved me some trouble if I had known the schedule.

　　→It might have saved me some trouble had I known the schedule.

　　②If he had caught the morning train, he would not have been late for the meeting.

　　→Had he caught the morning train, he would not have been late for the meeting.

　　二、虚拟语气的特殊用法

　　1．含蓄条件句的虚拟语气

有时在虚拟语气中假设的情况并不是以条件状语从句表示出来，而是通过一个介词、