虚拟语气表示说话人的愿望、假设、猜测或建议，而不表示客观存在的事实。虚拟语气通过谓语动词的特殊形式来表示，对虚拟语气在各种句式中的用法介绍如下：

　　A)、条件从句的虚拟语气

　　Eg. 如果我是你，我就不看电视了。

　　If I were you，I should/would not watch TV.

　　如果我做完家庭作业，我就去参加晚会。

　　If I did/had done my homework，I would go/have gone to the party.

　　如果你昨天晚上不看电视，就不会迟到了。

　　If you hadn't gone to the cinema，you would not have been late for class.

　　如果你努力地学习的话，你就会考试及格了。

　　If you had studied harder，you would have passed the exam.

　　The plants in our garden__________better if it had not rained so much last year.

　　A.had grown

　　B.would have grown

　　C.were growing

　　D.would grow

　　Note：

　　a)、条件从句中if 的省略，要倒装

　　如果条件从句的谓语动词包含有were或助动词、情态动词had，should，could，有时可将连词if省去，而将 条件从句的主语置于were，had，should，could之后。这种用法主要用于书面语，如：

　　a.与现在相反：If I were you (=Were I you)，I would go with him.

　　b.与过去相反：If I had had time then (=Had I had time then)，I would have gone with you.

　　c.与将来相反：If I were to visit/should visit/visited the Great Wall tomorrow，(=Were I to /Should I visit the Great Wall tomorrow)，I would take my son with me.

　　注意：在否定句中not不可提至主语前，如

　　(误)Weren't I here now，I would be in the bus.

　　(正)Were I not here now，I would be in the bus.

　　b)、without 可以代替条件从句

　　Eg.没有水和空气，我们就不能生存。

　　We would not live without water or air.

　　c)、混合虚拟条件句

　　如果条件从句的动作和主句的动作不是同时发生，主句和从句的谓语动词的形式应分别根据各自所表示的 时间加以调整。这种句子叫做混合虚拟条件句。如：

　　If he had followed my advice，he would be quite all rightnow.(从句述说过去，主句述说现在)

　　If China had not been liberated，the working people wouldstill be leading a miserable life.( 从句表示与过去的事实相反，主句说明与现在的事实相反)

　　d)省略主句，只保留if(only)的条件句

　　虚拟条件句中的表示结果的主句有时形式上可以省略，但意义仍然存在。这

　　种句子只保留一个if(only)条 件从句，表达说话人的强烈愿望。如：If(only)she

　　were my sister!她是我的妹妹就好了!

　　e)用but或but for引导含蓄条件句(but后跟从句，but for后跟短语：假如没有，要不是)