must的用法

巴士英语更新于2017-09-16 09:50  浏览 手机访问

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must 英[məst] 美[mʌst]

must基本意思是“必须;应该;必定;必然要”通常作为情态动词使用。有时也可以当名词使用。第三人称单数:musts 复数:musts 现在分词:musting 过去式:must 过去分词:must

1、作情态动词的的意思

要说must的用法,重点还是做为情态动词的用法。情态动词,没有人称或数的变化,后接动词原形。

a、表示必要性或重要,意思是“一定、必须”,通常用于肯定句及疑问句.如:

You must go to bed now.你现在必须睡觉了.

Must I start at once?我必须立刻出发吗?

He must finish all his work before the meeting. 他必须要在会议前完成所有的工作

b、表示依据某种规测或法律,意思是“必要,必须”,如:

You must fasten your seatbelt when you're driving.
你开车的时候一定要系上安全带。

You must show your passport to the immigration officer.
你必须要向移民官出示护照。

c、表示提出邀请或建议,意思是“务必”,如:

You must see a doctor, you've been sick for a week.
你务必要去看医生!你都已经病了一周了!

You must read that book! It's amazing!
你一定要去看那本书!真的是太棒了!

You must come to our party tonight! It'll be so much fun!
你一定要来参加我们今晚的派对!一定会非常有意思的!

d、用在疑问句,因不理解而愤怒,意思是“偏要”,如:

Why must she always interrupt me?
她为什么总是要打断我?

Why must you argue with each other everyday?
你们非要每天都争吵吗?

Why must you make so much noise?
你什么偏要制造那么多噪音?

e、表示必不可少的事物,必须要做的事,意思是“必须的,一定要的”,如:

You may think the insurance is unnecessary, but it's a must.
你可能认为保险没有必要,但却是必不可少的。

Eating Roast duck is a must if you come to Beijing.
如果你来北京,一定要尝尝烤鸭。

It's a must to try different kinds of beer in Germany.
在德国尝试不同种类的啤酒一定是必须要做的事。

2、must的否定式

must的否定式must not/mustn’t,意思是“不应该、禁止”,语气较强烈。如:

You must not smoke here.你不许在这里吸烟.

We mustn’t be late again.我们不应该再迟到了.

注意:must not/mustn't不是“不必要,不需要”的意思,切记。请看下面的must问答详解。

3、must的一般疑问句及回答

由must引出的一般疑问句,肯定回答用must,否定回答用needn’t,don’t need to或don’t have to均可,但不用mustn’t,因为mustn’t表示“不许、禁止”的意思,与问句的原意不符.如:

—Must I stay at home?我必须留在家里吗?
—Yes,you must.是的,你必须留在家里.
(No,you needn’t.或No,you don’t have to.)(不,不用了.)

如果是反意疑问句,疑问部分一般不用needn’t,而用mustn’t;否定回答时仍用needn’t,don’t need to或don’t have to.如:

—You must go on foot,mustn’t you?你必须走着去,是吗?
—Yes,I must.是的,是这样.
(No,I needn’t.或No,I don’t have to.) (不,不是的.)

4、表猜测

can't表达的是否定猜测,而must则表示肯定猜测,意思是某人或某物一定或肯定会怎么样。与can't一样,must主要用来表示对现在时间或是过去时间发生的事情的肯定猜测。

a、对现在时间的猜测

此时,must可以用来表示对现在的状态或动作进行猜测。如果是状态,must后面直接跟表状态的谓语动词即可;如果是动作,must后面的谓语动词则要采用be doing的形式。如:

状态:He must be over 40 years old. (他肯定有四十多岁了。)
动作:He must be reading in the library now. (他现在肯定正在图书馆看书。)

b、对过去时间的猜测

此时,must后面的谓语动词如果是状态,则采用“must have+表状态的动词的过去分词”;如果是动作,则采用“must have done”的形式;如果是过去进行的动作,则采用“must have been doing”的形式。如:

状态:He must have been in the bathroom when I called him last night.
动作:He must have finished his homework before dinner yesterday.
过去进行:He must have been listening to loud music, for he didn't answer my call.

5、用作名词

must也可以直接用作普通名词,表示“必须做的事,必需的东西”。如:

A raincoat is a must in the rainy season.  在雨季雨衣是必备之物。
His new novel is a must for all lovers of crime fiction.  他的新小说是罪案小说爱好者必须一读的。

6、must be\ must do 用于现在时

He keeps looking at you, he must like you.
他一直在看你,他一定是喜欢你吧

She looks so beautiful, she must be a model.
她好漂亮,她一定是模特吧

He has been working out for 5 years, he must be very strong.
他已经健身5年了,他一定特别强壮吧

7、must have been\ must have done用于过去时

He didn't show up last week, he must have been on vacation.
他上周一直没出现,他一定是去度假了

She must have been very excited, when her boyfriend proposed to her last night.
昨天晚上她男朋友向她求婚,她一定十分兴奋。

You got a 20% pay rise, you must have done a great job.
你的薪水涨了20%,你一定做得特别好吧!

8、must与have to的区别。

a、表示(主语)主观的义务或必要时用must;表示(主语)客观因素的义务或必要时用have to。have to含有“不得不”的意思。如:

I must be off. Thank you for your help. 我得走了。谢谢你的帮助。
We have to be there early. 我们得早点去那儿。

b、have to可以放在will后面构成将来时,而must则不能。例如:

他明天必须去那里。
误:He will must go there tomorrow.
正:He will have to go there tomorrow.
正:He must go there tomorrow.


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