虚拟语气表示说话人的主观愿望、猜测建议或与事实不符的假设。虚拟语气可分为三种：（1）一般虚拟 （2）混合虚拟（3）特殊句式

　　一．一般虚拟的构成：(省略if, 要将should/were/had 提到句首)

(1). 对现在的虚拟：

　　If I had time, I would attend the meeting.

　　If I were you, I would seize the chance to go abroad.

(2) .对过去的虚拟

If you had taken my advice, you would not have failed in the exam.

(3) 对将来的虚拟：

　　If you came tomorrow, we would have the meeting.

　　If it were to rain tomorrow, the sports meeting would be put off.

　　If he should not come tomorrow, we should put off the meeting till next day.

请注意倒装句：

Had we made good preparations, we might have succeeded.

=If we had made good preparations, we......

　　Had it not rained, we would have gone out for a walk.

Were I you, I would not do such a thing.

=If I were you, I......

　　二． 混合时态的虚拟：

　　（1） 不同时间的虚拟：If he had listened to me, he would not be in trouble now.

　　If he had told me yesterday, I should know what to do now.

　　(2) 虚拟与陈述的混合：

　　He could have passed the exam, but he wasn’t careful enough.

　　You should have come earlier, the bus left a moment ago.

　　三． 几个特殊句式：

　　(1).suggest, advise, recommend, propose, order, command, request, require, demand 后接that引导的宾语从句用虚拟语气。 宾语从句的谓语用（should ）do/do 。

　　He suggested that we (should) save money for the future.(insist的判断)

　　(2) It is suggested/advised/ordered/requested/required that –clause(should do/do)(主语从句)

　　(3) My advice/suggestion/request/requirement is that-clause (should do /do) （表语从句）

　　His suggestion/advice/request/requirement that –clause(should do/do ) is.. （同位语从句）

　　(4) It is natural/necessary/strange that-clause (should do/do)表惊奇、怀疑、惋惜、不满、理应如此等。

　　It’s strange that he should have missed the train. （表竟然）

　　It is important that we should learn from others.（表理应如此）

　　It is a pity that he should not go with us.(表惊讶、不满)

（5）wish 后接宾语从句使用虚拟语气

wish + that clause (did/were 与现在相反)

　　wish + that clause (would/could/might + do与将来相反)

　　wish + that clause ( had done 与过去相反)

　　I wish I could go with them tomorrow.

　　I wish I had never met him.

　　(6) It is (high/about) time + clause (did, should do )

　　It is (high/about) time we went home.

　　(7) would rather + clause (did 与现在或将来相反)；（had done 与过去相反）

　　I would rather you came tomorrow. I would rather you hadn’t told her the news.

　　(8) If only + clause ( did/were与现在相反) ((would/could/might + do与将来相反)

　　( had done 与过去相反) “要是。。。就好了“

If only he would come tomorrow! 

 If only I had taken her advice!

　　If only I were ten years younger!

　　(9) as if + clause (did/were 与现在相反) (would/could/might + do与将来相反)

　　( had done 与过去相反)

　　She treats Kate as if she were her own daughter.

　　They talked as if they had been friends for years.

(10) Without / but for + n.

= If it were not for +n. / if it hadn’t been for + n. (otherwise后从句同)

I would not have passed the exam without your help.

=If it hadn’t been for your help，I would not have passed the exam.