高中英语语法讲解--虚拟语气
1. 语气的定义和种类 （1）语气的定义
语气是动词的一种形式，它表示说话人对某一行为或事情的看法和态度。 （2）语气的种类 A. 陈述语气
表示动作或状态是现实的、确定的或符合事实的，用于陈述句、疑问句和某些感叹句。 We are not ready.
Did it rain all day yesterday? What a fine day today！ B. 祈使语气
表使说话人的建议、请求、邀请、命令等。 Be careful.
Don’t forget to close the window. Open the door, please. C. 虚拟语气
表使动作或状态不是客观存在的事实，而是说话人的主观愿望、假设或推测等。 2. 虚拟语气
一. 虚拟语气在条件句中的应用
学习虚拟语气在条件句中的用法之前我们必须清楚条件句的种类：条件句有真实条件句与非真实条件句(或称虚拟条件句)两种。真实条件句所表的假设是可能发生或实现的，句中的条件从句与结果主句都用陈述语气。如：
If it doesn’t rain tomorrow, I will go for a picnic. 假若明天不下雨，我就去野餐。 Oil floats if you pour it on water. 你如把油倒在水里，油就浮起来。 虚拟条件句所表的假设则是不可能或不大可能发生或实现的，句中的条件从句与结果主句皆须用虚拟语气。
条件从句 主句 should / would/could/might + 动词原形 should / would/could/might + have +过去分词 与现在事实相违背 过去式（动词是be用were） 与过去事实相违背 had + 过去分词 1) should + 动词原形 should / would/could/might + 动词原与未来事实相违背 2) were + 动词不定式 形 3) 过去式（动词是Be也可以用were） 1. 与现在事实相反的虚拟条件句，条件从句的谓语用动词的过去式 (be的过去式用
were), 主句的谓语用should （would, might， could）+动词原形。 如：
If it were not raining, we should go for a picnic.如果现在不下雨的话，我们就出去野餐了。 （事实是：天在下雨，我们不能出去野餐。表示愿望。）
If he came here, he might be able to help you. 如果他来这，他就能够帮助你了。 （事实是：他没来这，他不可能帮助你。表示对他的良好印象。）
2. 与过去事实相反的虚拟条件句，条件从句的谓语用had+过去分词，主句的谓语用should （ would, might， could）+ have ＋过去分词。
如： She would have gone to the party if she had been invited.
要是当初她被邀请的话，她就会去参加这次聚会了。
（事实是：当时没有人邀请她，因此，她没有来参加聚会。表示后悔。） If she hadn't called me, I would have overslept this morning. 今天早上，她要是不叫我的话，我就会睡过头了。
（事实是：她今天早上叫我了，我没有睡过头。表示感激。） 3. 与将来事实可能相反的虚拟条件句，条件从句的谓语用动词的过去式(be的过去式用were)； should＋动词原形；were to＋动词原形，主句用should （would, might， could）+动词原形。
如： If I were to be twenty years old next year, I would take the course of French. 明年我要是二十岁，我就会学法语。
（事实是：我现在已经老了，明年我学不了法语了。）
If it should fail, I would try again.要是失败了，我会再试一次。 （事实是：有可能失败，可我会再试。表示未知。）
虚拟过去式有时并不表示“不大可能实现的假设”，而是表示一种希望或不希望发生的动作。 如： If we caught the early train, we’d get there by lunch time.
假如我们赶上早班火车，到午饭时间我们就会到达那里了。(表希望) If we missed the train, we should have to wait an hour at the station.
假如我们赶不上这班火车，我们就得在车站等一小时。（表不希望） 4. 混合型的条件句
当条件从句与主句所表的时间不一致时，虚拟语气的形式应作相应的调整。主句和从句的谓语动词并不相互呼应，这种条件句叫混合条件句。较多见的混合型条件句是从句用过去完成时（指过去行为），而主句用一般时（指目前状态）。 He would pass the test if he had taken my advice．如果他听了我的劝告，他现在会通过考试。 If I had spoken to him yesterday, I should know what to do now. 假如昨天我对他说了，现在我就知道该怎么办了。
You would be much better now if you had taken my advice. 假如你接受了我的意见，你现在就会好得多。
如条件从句用if I were...，主句则可用表任何时间的虚拟形式。 如： If I were not busy, I would have come. 假如我不忙，我就会去了。(were表过去) If I were you, I would go.
假如我是你，我会去的。(were表现在) 二. 连词if的省略（倒装）
如果虚拟条件句的谓语部分有were，had和should时，可省略if，把were，had和should放到从句主语前面去，多见于书面语。
Had you not helped me， I should have failed.要是没有你的帮助，我就失败了。 Were you in my position, you would do the same. 假如你处在我的地位，你也会这样干的。 Should they attack us, we’ll wipe them out completely.
假如他们进攻我们，我们就把他们彻底消灭干净。
例：1. _________ he would have succeeded in the examination. A. Had he worked hard B. If he worked hard C. If he works hard
D. If he has worked hard
2. _______ it rain tomorrow, we would stay at home. A. Should B. Be C. Were D. Will 3. _______, he would teach us how to solve the problem. A. Were he here B. Was he here C. If he is D. Is he here 4. _________, we should be glad. A. Were they to arrive tomorrow B. They were to arrive tomorrow C. They would arrive tomorrow D. They arrive tomorrow
5. _______ the clouds, you would find the airplane in the sky easily. A .Were it not for B. If it had not been for C. If it were not D. Had it not been for 答案：1—5 AAAAA 三. 含蓄条件句
虚拟条件句中的条件从句有时不表出来，只暗含在上下文中，这种句子叫做含蓄条件句。含蓄条件句大体有三种情况。 1) 条件暗含在短语中。
如： But for your help we couldn’t have succeeded in the experiment.
如果没有你的帮助，我们的实验是不会成功的。(暗含在分词短词but for your help) What would I have done without you? 如没有你，我会怎么办呢？(条件暗含在介词短语without you 中)
It would be easier to do it this way. 这样做会比较容易。 (条件暗含在不定式短语 to do it this way中)
This same thing, happening in wartime, amount to disaster.
同样的事，如发生在战时，就会酿成大祸。(条件暗含在分词短语happening in wartime 中)
He must have the strength of a hippopotamus, or he never could have vanquished that great beast. 他一定是力大如河马，否则他绝不会击败那只庞大的野兽。(暗含条件是连词or) Alone, he would have been terrified. 如是单独一人，他是会感到害怕的。(暗含条件是alone) 2) 条件暗含在上下文中。
如： You might stay here forever. 你可以永远待在这儿。(可能暗含if you wanted to) We would have succeeded. 我们本来是会成功的。(可能暗含if we had kept trying)
Your reputation would be ruined. 你的名誉会败坏的。(可能暗含 if you should accept it) 3) 在不少情况下，虚拟式已变成习惯说法，很难找出其暗含的条件。 如： You wouldn’t know. 你不会知道。 I would like to come. 我愿意来。 四. 不用if引导的条件从句
虚拟条件句中的条件从句除用if引外，还可用when, unless, lest, suppose, as if, for fear, in case, on condition 等词语来引导。
如： The peasants prepared to feed the city when it should be freed. 农民已准备在这座城市解放后供给粮食。
Lest you should not have heard all, I shall begin at the beginning. 我怕你没有听全，所以我再从头开始讲一遍。
(完整版)高中英语语法虚拟语气讲解
