虚拟语气专题
（Subjunctive Mood）
1. 虚拟条件句中的虚拟语气：
条件从句
结果主句
与现在事实相反
if + 主语 + were/PT
主语 + would + be/V
与过去事实相反
if + 主语 + had been/PP
主语 + would + have been/PP
对将来进行推测
① if + 主语 + were/PT
主语 + would + be/V
② if + 主语 + were + INF
③ if + 主语 + should + be/V
注意：“对将来进行推测”中的 ① 和“与现在事实相反”在形式上相同，因此常需要通过语境，或条件从句中时间状语的差别来判断各自所属的类型，不可混淆。
1) 与现在事实相反：
1 If I were a white cloud, I would be the most beautiful one.
2 If he were indoor, he wouldn't feel so cold.
3 If I knew the answer to the questions, I would be a genuis.
4 If I had time, I would go to the movies with you.
2) 与过去事实相反：
1 If the weather had been fine yesterday, he would have been on a train to Beijing.
2 If you had been in my position, what would you have done to settle the dispute?
3 If we hadn't made adequate preparations, the conference wouldn't have been so successful.
4 If I had left sooner last night, I would have caught the last bus.
3) 对将来进行推测:
1 If he were here this evening, we would be wild with joy.
2 If I were to to the work, I would do it in a different way.
3 If she should know it, she would tell me.
2. 结果主句中的 would 常可替换为 should/might/could/must 等，它们的语法功能与 would 相同，不妨将它们视为 would 的“变体”，但它们能够依据语境中的具体情势，更加细致地体现出不同的语气差异。
3. 在虚拟条件从句中，可通过不同形式的 be 动词 (be, were, been) 后接 PresP(现分) 构成进行时态，表示“如果 … 正在 …”等，结果主句中的谓语仍用would，并可根据情况选用适当的时态（包括主从句均使用进行时态）。（Ref.P646）
1) If she were living a hard life, her family should@ be responsible for it.
（可将 should 视为 would 的“变体”,用上标“@”表示，文中出现的其它替换词均可依此类推。）
2) If human beings were not killing each other, we would be living a happy life.
3) If you hadn't been studying so hard, you would have failed the exam.
4. 当条件句中有 were/had/should/could 时，可以省略 if，同时将 were/had/should/could 放在主语前，形成倒装结构。（这种用法主要用于书面语中。）
1) Were it necessary, I might@ resign.
2) Had you informed me earlier, I wouldn 't have signed the contract.
3) Should I have time, I would call on her.
4) Could you meet Mary, you should@ not be able to recognize her.
5. 虚拟语气中的主句通常是陈述句，但也可以是疑问句、感叹句或祈使句。当条件从句的谓语动词为 should + V 时，主句往往是祈使句。注意，由于祈使句始终使用 V，故和上表所述状况存在差异，对上表是一种补充。（参考本文第 8 条）
1) If you had everything，would you be happy?
2) If he had married Alice, how happy he would have been!
3) If you were man enough, don 't give up.
4) If you should needresolve的名词形式 help, just tell me.
6. “could have + PP”结构的含义特殊性：在虚拟条件句中使用该结构时，could 是情态动词，表示“能够”，相当于 have been able to do sth。
1) If you could have prevented/had been able to prevent mistakes, you might@ have been more successful.
2) If I could have earned/had been able to earn enough money, I should@ have travelled over the world.
7. 在同一个句子中，不能一部分表示真实条件，另一部分表示非真实条件，否则就会破坏句子的一致性, 产生语病。（Ref.P647<①>）
1) If he is(×)/were(√) here, he would not let the matter end thid way.
2) If I had the book, I will(×)/should@(√) lend it to you.
8. 虚拟条件从句中不可使用 would，否则就会产生语病。但是，如果表示主语的某种愿望，虚拟条件从句中也可以用 would，相当于 be willing to，常指说话人不相信主语有这种愿望，即不相信主语“愿意”做这件事情等。注意，由于would + V，故和上表所述状况存在差异，对上表是一种补充。（参考本文第 5 条）
1) If they would have (×)/φ(√) had come yesterday, I should@ be very much obliged.
2) If he would/is willing to lend me the money, I would buy a car. (But I know he will be not willing to.)
  （判断方法：用 be willing to 替换 would，再分别验证是否存在语法和逻辑错误）
9. 对于错综时间条件句（特殊的虚拟条件句），由于主句和从句表示动作的发生时间不一致，所以主句和从句的谓语动词应根据各自不同的时间背景分别选用适当的虚拟语气形式。（Ref.P648<2>）
1) Had I taken the umbrella, I should@ not be wet now.（过去 → 现在）
2) If I were you, I wouldn't have missed the film last night.（现在 → 过去）
3) If you hesitated this moment, you might@ suffer in future.（现在 → 将来）
4) If Mary should arrived today, she must@ have started 3 days ago.（将来 → 过去）
5) If they had left home in early morning, they should@ arrive in half an hour.（过去 → 将来）
6) If the train had started last night, I would be sitting by the dinning table at home.（过去 → 现在进行）
10. 当虚拟条件句充当宾语从句时，虚拟条件句的主从句中谓语动词的形式均不受整句级（即宾语从句）谓语动词的影响。
1) I often tell her that if she had made another try, she might@ have been successful.
2) I will tell her that ......
3) I have told her that ......
11. 有关“无条件”的虚拟语气的句子：这里所谓的“无条件”，指的是句子在字面上并没有通常由 if 或 I wish 等引导的条件从句，但是在其深层结构或上下文语境中还是“有条件”的。最明显的特征就是常有结果主句，而无条件从句。这种条件可通过间接或“跳层”的方式由名词、动词、形容词、代词、介词、连词、现在分词、过去分词、不定式、祈使句、定语从句或上下文等表现出来。常用词有：with, without, only, but for, or, or else, but, otherwise, even, in case of, what if 等。（Ref.P649<3>）
1) With better equipment, we could@ have done it better.（介词短语）
2) They wouldn't have reached the agreement so easily without that common ground.
3) She said she would have come to the party, only she had an urgent matter to attend to.