have to

modal verb

/ˈhæv tə/, /ˈhæf tə/

动词形式

present simple I / you / we / they have to	/ˈhæv tə/, /ˈhæf tə/ /ˈhæv tə/, /ˈhæf tə/
he / she / it has to	/ˈhæz tə/, /ˈhæs tə/ /ˈhæz tə/, /ˈhæs tə/
past simple had to	/ˈhæd tə/, /ˈhæt tə/ /ˈhæd tə/, /ˈhæt tə/
-ing form having to	/ˈhævɪŋ tə/ /ˈhævɪŋ tə/

(also have got to)
used to show that you must do something必须；不得不
- Sorry, I've got to go.对不起，我必须走了。
- Did she have to pay a fine?她非得交罚款吗？
- You don't have to knock—just walk in.不必敲门，进来就是了。
- I haven't got to leave till seven.我不必赶在七点前离开。
- First, you have to think logically about your fears.首先，你得理性地看待自己的忧虑。
- I have to admit, the idea of marriage scares me.我不得不承认，一想到结婚我就害怕。
- Do you have to go?你非得走吗？
- (especially British English) Have you got to go?你非得走吗？
Express Yourself Asking about obligation
Asking about obligation咨询相关义务When you are unsure about what is expected of you in a situation, you can ask about obligations:不确定在某种情境下该做什么时可以询问应履行的义务：
- What time do we have to be home?我们必须在什么时候回到家？
- Are we supposed to show our ID cards?我们需要出示身份证吗？
- Is it necessary to apply for a visa?有必要申请签证吗？
- Is there a legal obligation to wear a bike helmet here?在这里骑自行车有没有法律规定要戴头盔？
Topics Permission and obligationa1
(also have got to especially in British English)
used to give advice or recommend something（劝告或建议时用）
- You simply have to get a new job.你就是得找份新工作。
- You've got to try this recipe—it's delicious.你得试试这种烹调法，味道很不错。
Topics Suggestions and advicea2
(also have got to especially in British English)
used to say that something must be true or must happen（表示一定真实或肯定发生）
- There has to be a reason for his strange behaviour.他的古怪行为一定事出有因。
- This war has got to end soon.这场战争必将很快结束。
used to suggest that an annoying event happens in order to annoy you, or that somebody does something in order to annoy you（用以暗示麻烦的事或某人有意捣蛋）
- Of course, it had to start raining as soon as we got to the beach.可恶的雨，我们一到海滩它就非得下起来。
- Do you have to hum so loudly? (= it is annoying)你非得用这么大嗓门哼唱不可吗？
Grammar Point modal verbs
modal verbs
- The modal verbs are can, could, may, might, must, ought to, shall, should, will and would. Dare, need, have to and used to also share some of the features of modal verbs.can、could、may、might、must、ought to、shall、should、will 和 would 均为情态动词。dare、need、have to 和 used to 亦具有情态动词的某些特性。
- Modal verbs have only one form. They have no -ing or -ed forms and do not add -s to the 3rd person singular form:情态动词只有一种形式，没有 -ing 或 -ed 形式，第三人称单数也不加 -s：
  He can speak three languages.他会说三种语言。
  She will try and visit tomorrow.她明天将设法去参观。
- Modal verbs are followed by the infinitive of another verb without to. The exceptions are ought to, have to and used to:情态动词后跟不带 to 的动词不定式，但 ought to、have to 和 used to 例外：
  You must find a job.你必须找到一份工作。
  You ought to stop smoking.你应当戒烟。
  I used to smoke but I gave up two years ago.我过去抽烟，但两年前就戒了。
- Questions are formed without do/does in the present, or did in the past:疑问句现在时不用 do/does，过去时不用 did：
  Can I invite Mary?我可以邀请玛丽吗？
  Should I have invited Mary?我本该邀请玛丽吗？
- Negative sentences are formed with not or the short form -n’t and do not use do/does or did.否定句用 not 或简约式 -n't，不用 do/does 或 did。
You will find more help with how to use modal verbs at the dictionary entries for each verb.情态动词的不同用法可参考本词典里各情态动词词条。
Grammar Point must / have (got) to / must not / don’t have to
must / have (got) to / must not / don’t have toNecessity and Obligation必要和义务
- Must and have (got) to are used in the present to say that something is necessary or should be done. Have to is more common in North American English, especially in speech:
  You must be home by 11 o’clock.你必须在 11 点之前回家。
  I must wash the car tomorrow.我明天必须洗汽车。
  I have to collect the children from school at 3 o’clock.我得在 3 点钟到学校接孩子。
  Nurses have to wear a uniform.护士必须穿制服。
- In British English there is a difference between them. Must is used to talk about what the speaker or listener wants, and have (got) to about rules, laws and other people’s wishes:
  I must finish this essay today. I’m going out tomorrow. 我今天一定要完成这篇论文，因为我明天要出去。
  I have to finish this essay today. We have to hand them in tomorrow. 我今天得完成这篇论文，因为我们明天必须交。
- There are no past or future forms of must. To talk about the past you use had to and has had to:
  I had to wait half an hour for a bus.我得等半小时的公共汽车。
  Will have to is used to talk about the future, or have to if an arrangement has already been made:
  We’ll have to borrow the money we need.我们需要的这笔钱只好去借了。
  I have to go to the dentist tomorrow.我明天得去看牙医。
- Questions with have to are formed using do:
  Do the children have to wear a uniform?孩子们必须穿制服吗？
  In negative sentences both must not and don’t have to are used, but with different meanings. Must not is used to tell somebody not to do something:
  Passengers must not undo their seat belts until the signs have been switched off.在标志关闭之前，乘客不得解开安全带。
  The short form mustn’t is used especially in British English:
  You mustn’t leave the gate open.你一定不要让大门敞开着。
  Don’t have to is used when it is not necessary to do something:
  You don’t have to pay for the tickets in advance.你不必预付票款。
  She doesn’t have to work at weekends.她周末不用上班。
Certainty肯定
- Both must and have to are used to say that you are certain about something. Have to is the usual verb used in North American English and this is becoming more frequent in British English in this meaning:
  He has (got) to be the worst actor on TV!他无疑是最糟糕的电视演员！
  (British English) This must be the most boring party I’ve ever been to.这无疑是我参加过的最无聊的聚会。
  If you are talking about the past, use must have:
  Your trip must have been fun!你这次旅行一定很开心吧！