must

modal verb

OPAL W

/məst/, strong form /mʌst/

Verb Forms

must not
mustn't	/ˈmʌsnt/ /ˈmʌsnt/

Idioms

used to say that something is necessary or very important (sometimes involving a rule or a law)（表示必要或很重要）必须
- All visitors must report to reception.所有访客必须到接待处报到。
- Cars must not be parked in front of the entrance (= it is not allowed).汽车不得停放在入口前（= 不允许）。
- (formal) I must ask you not to do that again.我得劝你别再那样做了。
- You mustn't say things like that.你千万别说那样的话。
- I must go and get the kids from school.我得去学校接孩子了。
- I must admit (= I feel that I should admit) I was surprised it cost so little.我得承认，这么便宜，真让我惊讶。
- (especially British English) Must you always question everything I say? (= it is annoying)我说什么你都非要提出质疑吗？
- ‘Do we have to finish this today?’ ‘Yes, you must.’“我们今天一定得完成这工作吗？”“对，必须完成。”
Note that the negative for the last example is ‘No, you don't have to.’
Express Yourself Asking about obligation
Asking about obligationWhen you are unsure about what is expected of you in a situation, you can ask about obligations:
- 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
used to say that something is likely or logical（表示很可能或符合逻辑）一定
- You must be hungry after all that walking.走了这么远的路，你一定饿了吧。
- He must have known (= surely he knew) what she wanted.他一定早已知道她想要什么了。
- I'm sorry, she's not here. She must have left already (= that must be the explanation).抱歉，她不在这儿。准是走了。
Grammar Point must / have (got) to / must not / don’t have to
must / have (got) to / must not / don’t have toNecessity and Obligation
- 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。
note at needCertainty
- 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！
(especially British English) used to recommend that somebody does something because you think it is a good idea（提出建议）应该，得
- You simply must read this book.这本书你可一定要看一看。
- We must get together soon for lunch.我们得马上集合去吃午饭。
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.
- Modal verbs have only one form. They have no -ing or -ed forms and do not add -s to the 3rd person singular form:
  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:
  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:
  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.
You will find more help with how to use modal verbs at the dictionary entries for each verb.
Topics Suggestions and adviceb1

Word OriginOld English mōste, past tense of mōt ‘may’, of Germanic origin; related to Dutch moeten and German müssen.

Idioms

if you must (do something)

used to say that somebody may do something but you do not really want them to（表示虽不赞同但可允许）如果你一定要（那么做）
- ‘Can I smoke?’ ‘If you must.’“我可以抽烟吗？”“好吧，如果你一定要抽的话。”
- It's from my boyfriend, if you must know.倘使你一定要知道的话，这是我男朋友给的。

must-see/must-read/must-have, etc.

used to tell people that something is so good or interesting that they should see, read, get it, etc.必看（或必读、必备等）
- Sydney is one of the world's must-see cities.悉尼是世界上的必游城市之一。
- The magazine is a must-read in the show business world.这份杂志是演艺界人士的必读刊物。
- This is on my must-do list.这是我的必做清单上的事情。
- a must-have for any fan任何粉丝的必备品

needs must (when the Devil drives)

(saying) in certain situations it is necessary for you to do something that you do not like or enjoy（情势所迫）只好如此；不得已而为之