动词的语气用法讲解.doc

一、概述
语气是一种动词形式，是讲话人对说话内容的看法的语法范畴，英语中有三种语气，即陈述语气、祈使语气和虚拟语气。
二、语气的种类
1、陈述语气（indicative mood）
表示谓语动词所表达的动作或状态是符合客观事实的，也就是说把动作或状态当作事实表达出来。
There are two sides to every question. 每个问题都有两个方面。
She is a very good student. 她是一个很好的学生。
2、祈使语气（imperative mood）
表示讲话人对对方的请求、命令号召、劝告、警告、禁止。
   Don’t be late for class. 上课不要迟到。
   Take a seat, please.请坐。
3、虚拟语气（subjunctive mood）
是一种特殊的谓语动词形式，用来表示一种假设、愿望、建议、请求、命令、猜测、可能、空想等非真实情况。
   How I wish I were a bird！我多么希望我是一只小鸟！
   I suggest you should go to have a walk.我建议你去散步。
三、虚拟语气在非真实条件从句中的用法
非真实条件句所假设的是不可能有的条件，或者是与事实相反的条件，这又可以分为三种情况。
1、表示与现在事实相反
谓语动词的形式如下:
条 件 从 句
主     句
动词过去式(be用were)
would/should/could/might+动词原形
If there were no subjunctive mood, English would be easier.如果没有虚拟语气，英语会容易学。
I'd come too if I had time to spare.我如果抽得出时间的话，我也愿意来。（与现在事实相反）
If everyone in the country knew first aid，many lives would be saved.如果每个国民都懂得怎样急救，那么就可以挽救许多人的生命了。（与现在事实相反）
If I were you, I should do it.如果我是你的话，我就要做这件事。（与现在事实相反）
2、表示与过去事实相反
谓语动词的形式如下:
条 件 从 句
主     句
had+过去分词
would/should/could/might+ have+过去分词
-If he had been warned, he would not have taken that food.如果不是告诫他，他会把那些食物都吃了。（与过去事实相反）
-Luckily he was sent to the hospital immediately. 幸运的是，他被及时送往了医院。
I didn't see your sister at the meeting. If she had come, she would have met my brother.我在会上没见到你姐姐。如果她来了的话，她就见到我哥哥了。（与过去事实相反）
You didn't let me drive. If we had driven in turn. You wouldn't have got so tired.你不让我开车，如果我们轮流开车的话，你不会这么累。（与过去事实相反）
3、表示与将来事实相反
谓语动词的形式如下:
条 件 从 句
主     句
动词过去式(should/could+动词原形；were to+动词原形)
would/should/could/might+动词原形
 If the peasants could farm the land themselves, food production would be much higher. 如果农民能为自己种地，粮食产量还会更高。
If it were Sunday tomorrow, I should go to see a film. 明天要是星期天，我会去看场电影的。
If you were to come tomorrow, I should ask you to help me with my work.如果你明天来，我就请你帮助我做这件工作。（与将来事实相反）
If it had been raining yesterday, I would not have come here.如果昨天还在下雨的话，我就不会到这里来。
二、错综时间条件句
有时主句和从句的谓语动词并不是相互呼应，这种条件句叫做混合条件句,又称为错综时间条件句。
If the doctor hadn't come, the patient would be dead by now.要是大夫不来的话，病人现在就会死去了。（条件句过去-主句将来）
If China had not been liberated, the working people would still be leading a miserable life.如果中国没被解放，劳动人民现在仍会过着悲惨的生活。（条件句过去-主句现在）
If Mary should arrive today, she must have started in future.如果玛丽今天到的话，那她一定在三天前就动身了。（条件句现在-主句过去）
三、含蓄条件句
所谓含蓄条件句，是指if条件从句没有被明确表达出来的条件，具体分为下列几种情况：
1、通过不定式短语表示条件
You would be a fool to refuse his offer. (=If you should refuse his offer, you would be a fool.) 要是你拒绝他的建议，就太傻了。
It would be a mistake not to help him. (=It would be a mistake if we did not help him.)如果不帮助他那就会是一个错误。
It would hurt us to act hastily. (=…if we were to act hastily.)仓促行事会对我们不利的。
2、通过介词短语表达条件
用介词without（或with no）, but for 等表示“如果没有”。
Without electricity, human life would be quite different today.要是没有点，人类今天生活将会大相径庭。
Without steel(=If there were no steel),there would be no industry.没有钢铁，就不可能有工业。
Della couldn’t have lived through Christmas without giving Jim a present. (=…if she hadn't given Jim a present.德拉不送给吉姆一件礼物，他简直过不了圣诞节。
But for the storm I would have arrived much earlier. (=If it had not been for the storm…)要不是那场暴雨，我早就到达了。
3、通过连词otherwise, or, but, but that, though, once等表达条件
 Yesterday, Jane walked away from the discussion. Otherwise, she might have said something she would regret later.昨天，詹离开了讨论会。否则，她会说些自己后悔的事。
She came to town yesterday, otherwise/or I would not have met her. (otherwise/or =if she hadn't come…)昨天她到城里来了，不然我就不会遇见她了。
I would have attended the meeting, but I have been too busy. (=…if I had not been too busy)我本来要参加会议的，只是太忙了。
Einstein cared little for money, though he could have been very rich. (though=if he had cared for money…)爱因斯坦对钱不感兴趣，尽管他本来可以成为非常富有的人。
Once lost(=If it were once lost),it would be hard to find.一旦失去，便不容易找到了。
We should have come, but that we had an accident. (=…if we hadn't had an accident)要不是出了事故，我们早就来了。
4、通过分词短语表达条件
Given more attention, the trees could have grown better. (=if they had been given more attention…)倘若给予更多的关心，这些树本来可以生长得更好的。
Supposing it should rain, we would still go. (=If it were to/should rain…)假如下雨的话，我们还是要去。
5、无词句暗示条件
Such mistakes could have been avoided.这种错误本来可以避免的。（暗示条件从句if we had been more careful）
It was so quiet, you could have heard a pin drop.是那样的安静，掉根针你都能听得见。（暗示条件从句if it had dropped to the ground）
四、if的省略
如果条件从句的谓语动词中含有were，had，should，可省略连词if，把were，had，should放在主语前构成倒装。如果条件从句是否定式，倒装时只能把not放在主语之后，不能用缩写式把not放在主语之前。
Were I you (=If I were you), I would do more practice after class. 如果我是你，我会在课下多做练习。
Had you arrived (= f you had arrived) at the station ten minutes earlier, you could have caught the train. 如果你早到车站10分钟，你就赶上火车了。
Should he come (=If he should come), tell him to ring me up.他要是来了，让他给我打个电话