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情态动词must的用法

作者: admin来源: 网络文章 时间: 2016-09-13

1. 表示义务、命令或必要

主要用于用于肯定句、否定句疑问句。具体用法如下:

(1)意为“必须”。如:

Soldiers must obey orders. 军人必须服从命令。

Something must be done to stop pollution. 必须采取措施来防止污染。(可跟被动语态

I think I must be going. 我想我得走了。(可跟进行时态)

注:must 和have to 的用法及区别:

must 和have to 都表示“必须”,有时二者可以通用,如:

I must / have to leave now. 我得走了。

must表示说话人的主观看法,have to 表示客观的需要。如:

I feel I must write to thank you for your help. 我觉得我必须写信感谢你对我的帮助。

It is raining hard. You have to take an umbrella. 雨下得很大,你得带把伞。

must只有现在时形式;have to有更多时态。如:

We had to be there at eight. 我们八点钟必须到那儿。

“You'll have to get off here,” the conductor said. “你得在这里下车了,”售票员说。

must用于宾语从句或间接引语中也可表示过去情况。如:

He said that he must buy a gift for Mary. 他说他必须给玛丽买个礼物。

She insists that I must do it by myself. 他坚持这事我必须独立完成。

mustn't表示“禁止”“不许”;表示“不必”时,要用have to的各种形式。如:

You must not go there. 你不准去那儿。

We mustn't smoke here, must we? 我们在这儿绝不能吸烟,是吗?

We don't have to buy a new radio. 我们不必买新收音机了。

⑤以must开头的疑问句,肯定回答用must, 否定回答用needn't 或don't have to.如:

—Must I do it? 我一定要做这件事吗?

—Yes, you must. (No, you needn't. / No, you don't have to.) 是的,一定要做。(不必。)

(2)意为“应当”。如:

We must have a discussion about it before making a decision. 再作决定之前我们应该讨论一下。

You must read the book. 你应该读那本书。

(3)表示必然性。如:

Man must die. 人必有一死。

What must be will be. 注定要发生的事总要发生。

(4)表示与说话人愿望相反及不耐烦,意为“偏要”“偏偏”。如:

Why must she keep on asking? 他干吗非要问个不停?

We were ready to leave, the neighbor must come and chatter. 我们刚准备好要走, 邻居偏偏过来聊天。

 

2. 表示推测

must表示推测通常只用于肯定句,意为“准是”、“一定”,在否定句或疑问句用can。 如:

(1) must+动词原形表示对现在情况的推测。如:

You must be tired after your long journey. 你走了这么远的路,一定很累。

It must be true. 那必定是真的。

The man she married must have a lot of money. 她嫁的那个人一定有不少钱。

(2) must+ have+ 动词的过去分词,表示对过去事情的推测。如:

We must have taken the wrong road. 我们一定走错路了。

He must have arrived there. 他必已到达那儿了。

(3) must+ 进行式。

表示对正在发生的事情的推测。如:

Hurry up! Mother must be waiting anxiously. 快点!妈妈一定等急了。

有时表示“即将┅”,“将要┅”如:

I must be leaving now. 我得走了。.英语语法网 www.yingyuyufa.com

有时must+ 进行式用来表示“老是在(干某事)”,如:

Why must you always be finding fault with others? 你为什么老是挑别人的毛病?

(4) must+ 完成进行式,表示“准是一直在┅”如:

Someone must have been smoking here.一定有人一直在这里抽烟。

They are sweating all over, They must have been playing football on the playground. 他们浑身是汗,准时在操场踢足球来着。

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