Word · CEFR A1 · Frequency #111
must
必须；一定
used for strong necessity or a conclusion believed to be certain
可表示强烈的必要性，也可表示有充分依据的肯定推断。
In use
You must wear a seat belt in the car.
She must be tired after such a long day.
Visitors must not enter this room.
must + [verb] (necessity)
must表示主观义务或必要性，否定形式用mustn't表示禁止。
You must finish your homework before watching TV.
你必须先完成作业才能看电视。
mustn't + [verb] (prohibition)
mustn't是must的否定形式，强调禁止。表示‘不必’时用don't have to。
You mustn't park here; it's a fire lane.
你不能在这里停车，这是消防通道。
must + be + [adjective/noun] (logical conclusion)
must表示对现在的肯定推测，语气较强。
He's been working all day; he must be tired.
他工作了一整天，肯定累了。
Verb forms
base must · third person must · -ing · past must · past participle undefined
情态动词 must 没有 -ing 形式或过去分词，也不使用普通的第三人称单数 -s 变化。
Common mistakes
I must go to the store yesterday.I had to go to the store yesterday.
must 没有过去时形式，需要用 had to 表示过去的必要性。
You mustn't finish your homework; it's not required.You don't have to finish your homework; it's not required.
mustn't 表示禁止，而‘不必’应该用 don't have to 或 needn't。
Connections
Collocations
- must have
- 必须有；一定有的
- A passport is a must-have for international travel.护照是国际旅行的必备品。
- must be
- 一定是；肯定是
- You must be tired after such a long journey.这么长的旅途之后你一定很累。
- must do
- 必须做
- This is a must-do task before the deadline.这是在截止日期前必须完成的任务。
- must see
- 必看
- That new movie is a must-see for all film lovers.那部新电影是所有电影爱好者的必看之作。
- must read
- 必读
- This book is a must-read for anyone interested in history.这本书是对历史感兴趣的读者的必读之作。
- must win
- 必须赢；必胜
Learner notes
Memory Tip
must发音似'骂死他'，用来强调必须做的要求。
Context & Register
语域：neutral 常见场景：日常交流、书面规则、逻辑推理 must 是英语中最基本的情态动词之一，表达必要性或强推测，A1 级别学习者即可使用。它既适用于口语对话，也常见于正式书面语，因此语域归为中性。
Grammar Note
must 后接不带 to 的动词原形。mustn't 表示“禁止”，而“不必”通常用 don't have to 或 needn't。
Pronunciation & Spelling
All words end in -ust and share the same vowel sound /ʌ/, so they rhyme with 'must'.
High-value vocabulary
该词属于 Oxford 核心词汇，值得优先掌握常见搭配和句型。
Usage priority
Collins 词频等级为 5，建议结合例句记忆，而不是只背中文释义。
Dictionary facts from BRIDGEDICT_CURATED_MODAL, CEFR_J, DICTIONARY_API_DEV.