在if引导的表示虚拟的条件状语从句中，有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if 省去，而 将had , should, were 等词提到主语之前，即用倒装结构。
1). 原句：If she were younger, she would do it.
去If：Were she younger, she would do it. (把动词were移到主语she的前面)
2). 原句：If he had tried it, he could have done it.
去If：Had he tried it, he could have done it.(把had移到主语he的前面)
3).Had he worked harder, he would have got through the exams.
4).Were he to leave today, he would get there by Friday.
5).Were I in your place, I wouldn’t do that.
6).Had I seen the film, I would have discussed it with them last night.
7).Were I a bird, I could fly freely.
8).Should it rain next week the farmers would have a good harvest.
假如虚拟条件句中有were, had或should时，把它们放在if的地方上;但假如条件句中没were, had或should不可以用倒装。
⑴、Should it rain tomorrow, what should we do?如果明天下雨的话，我 们如何解决呢?
⑵、Were I you, I would have asked him for some advice.如果我是你的话，我 就向他请教了。
⑶、Were he to do this work by himself, he would get a lot of money.假如他一个人可以做此工作，他就会得到一些钱。
⑴、If any person be guilty of a crime, the court shall have the right to appeal. (其他人犯罪，法院有权起诉。)
Be any person guilty of a crime, the court shall have the right to appeal.
⑵、Whether she be right or wrong, she will have my unanswering support. (不管她是对还是错，我都会支持她的。)
Be she right or wrong, she will have my unanswering support.
⑶、____ ,I will take her as my wife.(答案看最后★)
[A]Were she rich or poor
[B]Being rich or poor
[C]Be she poor or rich
[D]Whether is she poor or rich
注意：有时虚拟条件句并没来if 从句表示出来，而是用介词短语(otherwise, or, without, but for)、上下文或其它方法来表示。
⑴、We didn’t know his telephone number; otherwise we would have telephoned him.
⑵、Without you help, I wouldn’t have achieved so much.
⑶、But for your help, I would not have succeeded.
1. I could help you. (只有主句)
2. If I had time. (只有从句)
3. She should have come to the meeting. (只有主句)
4. If he had much more money. (只有从句)