如果从句表示的动作发生在过去，用过去完成时；指现在状况，则用过去时，指将来则用过去将来时。例如：
   
   He looked as if he were an artist.
   
   He speaks English so fluently as if he had studied English in England.
   
   Even if he were here, he could not solve the problem.
   
   在上述三种主语从句中，should应意为“应该”，“竟然”，可以省去，但不可换用would,主句所用动词的时态不限。注意：这种从句表示的是事实。如果说话人对这种事实表现出惊奇的情感，就可用虚拟语气。反之，如果不表示惊奇等情感，that 从句也可陈述语气，例如：
   
   It is strange that he did not come yesterday.
   
   It is a pity that you can’t swim.
   
   六、虚拟语气用于定语从句
   
   这种从句常用在It is (high) time (that)…句型中，定语从句的谓语动词用过去式，或should+动词原形（should不能省略，be 用were)来表示，意为“（现在）该……”。例如：
   
   It is (high) time we left (should leave).
   
   It is high time we were going.
   
   七、虚拟语气用于if only 引导的感叹句中
   
   If only I had taken his advice. 我要是听他的话就好了。
   
   If only I were a bird.我如果是一只鸟就好了。
   
   八、虚拟语气在简单句中的应用
   
   1）情态动词的过去式用于现在进行时，表示说话人谦虚，客气，有礼貌或语气委婉，常出现在日常生活中，例如：
   
   Would you be kind enough to open the door?
   
   2）用于一些习惯表达法中，例如：
   
   Would you like a cup of tea?
   
   I would rather not tell you.
   
   You had better go now.
   
   3）用“may+动词原形”表示“祝愿”。may 必须置于句首，例如：
   
   May you be happy!
   
   May you succeed!
   
   
   练习 选择最佳答案填空：
   
   1.The guard at the gate insisted that everybody _____ the rules.
   
   A. obeys B. obey C. will obey D. would obey
   
   2. If she had worked harder, she _____.
   
   A. would succeed B. had succeeded
   
   C. should succeed D. would have succeeded
   
   3. I wish I _____ you yesterday.
   
   A. seen B. did see C. had seen D. were to see
   
   4. You didn’t let me drive. If we _____ in turn, you ____

_ so tired.
   
   A. drove, didn’t get B. were driving, wouldn’t get
   
   C. drove, wouldn’t get D. had driven, wouldn’t have got
   
   5. – I stayed at a hotel while in New York.
   
   -- Oh, did you? You _____ with Barbara.
   
   A. could have stayed B. could stay
   
   C. would stay D. must have stayed
   
   6. I was really anxious about you. You _____ home without a word.
   
   A. mustn't leave B. shouldn’t have left
   
   C. ought not to have left D. should have left



 

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