虛擬語氣（Subjunctive mood）

      ①用來表示說話人所說的話不是一個事實，而是一種假設，推測，懷疑；

      ②是表示說話人的愿望，要求，命令，建議等。

掌握基本定義后，我們再來看看常見的類型：

一、虛擬語氣的常見形式

（1）if條件從句+主句

      1. If it were not raining, we should go for a picnic.

      2.She would have gone to the party if she had been invited.

      3.If it should fail, I would try again.

      4.If you should not come tomorrow, we would put off the meeting till next week.

      Attention:在虛擬語氣的從句中，動詞be的過去時態一律用were, 不用was，即在從句中be用were代替.

e.g:如果他在這兒，一切都會好起來。

      If he were here, everything would be all right.

（2）常用虛擬語氣的句型（命令，要求，建議等）

1. 動詞 + 賓語從句

      一個堅持：insist;

      兩個命令：order, command;

      三個建議：suggest, propose, advise;

      四個要求：desire, demand, ask, require

      I propose that we (should) set a dead line for handing in the plans.

      I suggest that we (should) set off at once.

      I insisted that we (should) decide what to do with him.

      Attention:虛擬語氣形式：(should) + 動詞原形

2. It is (was) + 上述動詞的過去分詞 + that主語從句

      It is demanded that he (should) leave at once.

      It is requested that she (should) give a performance at the party.

3. Order(suggestion, idea, proposal,advise)  + be + 表語從句

      My advice is that we (should) send for a doctor.

      Our suggestion is that you (should) be first to go.

4. It is (was) + important / necessary / strange / surprising / natural / possible / a pity / no wonder + that 主語從句

      It is best that he (should) set off at once.

      It is important that everybody (should) be told all the facts.

二、虛擬語氣的三種活用現象

（一）、含蓄條件句

      含蓄條件句就是虛擬條件暗含在短語或上下文中，從句不表現出來。這時，必須根據句中表述的意義以及某些特定的信息詞來進行判斷。

1.Without electricity, human life would be quite different today.

      A. is      B. will be      C. would have been     D. would be

      Without electricity = If there were no electricity

（二）、時間錯綜句

      從句與主句或上下文所表述的時間不一致。在這種情況下，我們切不可照搬某種形式，而應該按照句中所表述的時間關系，再選擇相應的虛擬形式。例如：

If the flower had been watered, it wouldn’t die now. 

        A. wouldn’t die                     B. is dead  

        C. had been dead                 D. will not die

（三）、虛實錯綜句

      虛實錯綜句是指虛擬現象與客觀事實錯綜交織在一起的句子，需要細心判斷哪一處是虛擬語氣，哪一處應使用陳述語氣。

They might have left earlier, but the car wasn’t ready.

        A. can have left                     B.may have left  

        C. will have left                     D. might have left

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