Have to的用法都有哪些
ave to 是一个比较特殊的情态习语，虽然也具有情态动词的功能，但却与其他的情态动词不同。它有人称、数和时态的变化，其否定式和疑问式的构成方式也与情态动词不一样。同学们在使用have to 时必须弄清它的真面目，否则容易出错。Have to的用法有哪些呢?本文是学习啦小编整理Have to的用法的资料，仅供参考。
Have to的用法
have to表示客观需要做的事情,意思是“必须”、“不得不”.后跟动词原形,有人称、
时态和数的变化,与情态动词 must 近义.
一、 have to 的陈述句形式
A、 肯定式：have to + 动词原形
1、 I have to tidy my room.我得整理房间.
2、 She has to help with the washing.她得帮忙洗衣服.
B、 否定式：don't (doesn't) + haveto + 动词原形
1、You don't have to go if you don't want to.如果你不想去,你就不必去.
2、He doesn't have to stay at home all day.他不必整天呆在家里.
二、have to 的一般疑问句形式及简略答语
have to的一般疑问形式必须借助助动词 do 或 does：
1、 Do you have to look after your sister?你得照看你妹妹么?
Yes,I do./ No,I don't.是的,我得照看./不,我不必照看.
2、 Does Jim have to do his homework?吉姆必须做家庭作业么?
Yes,he does./ No,he doesn't.是,他必须做./不,他不必做.
三、haveto 的特殊疑问句形式
1、 What do you have to do on Sundays?在星期天你得干什么?
2、 Why does she have to move to Paris?她为什么得迁往巴黎?
3、 Where do they have to work?他们必须在哪里工作?
四、haveto 可用于各种时态
A、一般现在时：I have to visit Mr Wang tomorrow.
明天我得去拜访王先生.
B、一般过去时：That night we had to walk home because there was no bus.
那天晚上我们不得不步行回家,因为没有公共汽车.
C、一般将来时：We'll have to ask Zhang Ming instead.
我们得请张明代替.
D、与may 连用：I think he may have to help his Dad in the garden.
我想他可能得在花园里帮他爸爸干活.
五、have to 与 must 的用法区别
A、 have to 比较强调客观需要,而 must 着重说明主观看法.
1、 My mother is ill.I have to look after her at home.
妈妈病了,我得在家照看她.
2、 You must finish your homework first.
你必须先完成作业.
B、 have to 有时态和人称变化,而 must 则没有.
1、 Mary has to water the trees.
玛莉得浇树.
2、 He must bring a picnic tomorrow.
他明天得带野餐.
C、must 有“推测”之意,而 have to 则没有.
He must be in the classroom.
他一定在教室里.
have to 的用法
一、have to 与其他情态动词一样也是后接动词原形，表示外界的
强制作用，强调被迫性。含有不情愿的色彩，常译为“必须，不得不”。
二、have to 可用于多种时态，而且不同时态使用不同的形式：一般现在时中，主语为第三人称单数时用has to 一般过去时中，用 had to。 have to 还可以用在其他的情态动词之后。例如： I have to do some washing. 我必须洗洗衣服。 She has to look after her little sister. 她不得不照顾她的小妹妹。 I had to do my homework last night. 昨晚我不得不做作业。 I think he may have to help his Dad in the garden. 我想他可能不得不在花园里帮他爸爸。
三、have to 的否定式和疑问式一般要借用助动词do的适当形式构成。have to 的否定式是don’t have to; has to 的否定式是doesn’t have to; had to 的否定式是didn’t have to。have to的疑问式同样也借用助动词do的相应形式构成。例如： He doesn’t have to do the homework now. 他没有必要现在做作业。 —Do I have to go there now? 我现在就得去那儿吗? —Yes, you do. (No, you don’t have to.) 是的，你必须去。(不，你不必。) We didn’t have to answer the question yesterday. 昨天我们没有必要回答这个问题。
注：情态习语是助动词、不定式或副词的组合。
四、翻译下面的句子。
1.我们必须自己动手去做。
2.玛丽必须在英语学习上努力吗?
3.上周日他不得不早起。
4.你没必要为你的功课担心。
5.彼得很累，不得不坐下来休息一会儿。
6.昨天他不得不待在家里。
7.他不得不跑回学校取他的作业本。
8.你必须早些离开吗?
9.我没必要躺在床上。
10.我们必须认真听老师讲课。
keys:
1. We have to do it ourselves.
2. Does Mary have to study hard at English?
3. He had to get up early last Sunday.
4. You don’t have to worry about your lessons.
5.Peter was very tired and he had to sit down and have a rest.
6. He had to stay at home yesterday.
7.Hehad to run back to school to get his exercise-books.
8. Did you have to leave early?
9. I don’t have to stay in bed.
10.We have to listen to the teachers carefully.
must和have to用法比较讲解
(1)must表示“必须”，“应该”。否定式must not(mustn't)表示“不应该”，“不许可”，“不准”,“禁止”等。在回答带有must的问句时，否定式常用need not(needn't)或don't have to 表示“不必”，而不用must not (mustn't)。 The work must be finished as soon as possible.这件工作必须尽快完成。 You mustn't speak like that.你不能那样说话。
—Must I be home before eight o'clock? 8点之前我必须回家吗?
—Yes, you must./No, you needn't./No, you don't have to. 是的，必须回家。/不，不必了。
(2)must表推测，
①一般只用于肯定句中，译成汉语“一定”，“必定”。
There must be some mistakes.肯定有一些错误。
You must be very tired.你一定很累了。
②如果表示对过去事情的推测，就用"must+完成时"。
You must have left your umbrella in the theatre.你一定把雨伞丢在剧院里了。
His car is still here. He must have gone by bus.他的车还在这里，他一定乘公共汽车走了。
③当must表推测之意时，其否定形式常用can not而不用must not。
He can't have been to your home. He doesn't know your address.他不可能到过你家，因为他不知道你的住址。
What can he be doing at this time of night?夜晚都到这个时候了，他究竟在干什么呢?
(3)must表必然性
You must catch cold if you don't put on more clothes.如果你不多穿些衣服，必然感冒。
All men must die.人固有一死。
Truth must be out.真相总会大白。
(4)have to表示“必须”，“不得不”，在这个意义上与must很接近，但must表示的是说话人的主观看法，而have to 表示的却是客观需要。
I have to go now.我得走了。(客观需要)
I must go now.我必须走。(主观看法)
You have to work hard to make a living.为了谋生你就得努力工作。(客观需要)
You must do what I tell you.你必须按照我告诉你的去做。(主观要求)
(5)have to 有更多的时态形式：现在时，过去时，将来时等，而must只有现在时形式。
We had to be there at 8.我们得8点到那里。
I shall have to go to school tomorrow.明天我得去上学了。
(6)have to 不能代替表推测的must，但在虚拟条件句中用had had to+动词原形表示与过去相反的情况。
You must be joking.你一定是在开玩笑。(不能用have to)
If I had had to do the work, I should have done it in a different way.
如果我不得不做这项工作，我会以不同的方式去做。(不能用must)
If I had had to run the factory, I would have had it run by able men.如果我得管理那家工厂的话，我就会让能人来管。(不能用must)
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