must
must — modal verb
1. Describes a situation where a rule, a law, or a practical need requires somethin
Describes a situation where a rule, a law, or a practical need requires something — for example, fastening a seatbelt because the law demands it, or sending a form before a closing date.
All passengers must fasten their seat belts during takeoff and landing.
must + base verb — rule or law obligation
Felix must finish his homework before he can watch television.
You must not park your car in front of the hospital entrance.
Application forms must be received by the end of February.
Students must wear their ID cards at all times while on campus.
- have to
more common in everyday speech for describing obligations; works in all tenses
- need to
slightly weaker than 'must', focuses on what is necessary rather than what is required by rule
- be required to
more formal; common in official notices and regulations
- must not
the direct negative — forbids the action
- do not have to
indicates that something is not necessary, not that it is forbidden
文法句型
must + base verb
must not + base verb (prohibition)
must + be + past participle (passive obligation)
用法筆記
Must has no past-tense form. For past obligation, use 'had to' (e.g., 'I had to leave early yesterday'). For prohibition in the past, use 'was / were not allowed to' (e.g., 'We were not allowed to park there'). Must is also not used with 'do/does/did' in questions or negatives — the negative is must not (contracted mustn't).
常見錯誤
2. used to show that you have made a strong decision to do something and will not l
used to show that you have made a strong decision to do something and will not let anything stop you — for example, promising yourself to quit smoking or to save money each month.
I must call my grandmother more often — I keep forgetting.
must + base verb — self-imposed personal intention
Christopher must stop staying up so late or his health will suffer.
We must save at least two hundred dollars before the summer trip.
I must remember to buy eggs and milk on the way home.
- have got to
more informal; common in British English for personal intentions
- be determined to
conveys the same strong resolve but works in all tenses
- will
less forceful; a simple statement of future action rather than a strong intention
文法句型
must + base verb
用法筆記
This sense expresses a personal resolve, not an external obligation. For past intentions, use 'was determined to' (e.g., 'I was determined to finish the marathon').
3. used before a verb to make your statement feel more forceful or emotionally char
used before a verb to make your statement feel more forceful or emotionally charged — for example, insisting that something is true, expressing surprise, or adding weight to an opinion.
I must say, I am really impressed by your presentation.
must say — fixed emphatic phrase for emotional force
I must admit, I was completely wrong about the election result.
must admit / must say — fixed emphatic phrase
You must understand that this decision was not easy for anyone.
You must let me thank you properly for everything you have done.
- really
adverb that can add similar force: 'You really should see the sunset'
- simply must
more emphatic version of 'must'
文法句型
must + base verb
must admit / must say
must + be + complement
用法筆記
Distinguish from sense 5 (LOGICAL DEDUCTION): in this emphasis sense, 'must' adds emotional force to a statement the speaker already knows to be true, rather than drawing a conclusion from evidence. Common fixed phrases include 'I must say', 'I must admit', and 'you must know'.
4. used to tell someone that you strongly believe they will enjoy or benefit from s
used to tell someone that you strongly believe they will enjoy or benefit from something — for example, suggesting a film, a restaurant, or an experience with enthusiasm.
You must try the chocolate cake at that little café downtown.
must + base verb — enthusiastic suggestion
Adina told me, 'You must read this novel — you will love it.'
You must visit the night market if you ever go to Taichung.
If you enjoy hiking, you must try the trail up Mount Jade.
文法句型
must + base verb
用法筆記
This sense is only used in the second person ('you must...') or reported speech about a recommendation ('She said I must...'). Unlike sense 1 (NECESSITY), there is no external rule — the speaker is simply expressing personal enthusiasm.
常見錯誤
5. Expresses near-certainty based on clear evidence — for example, hearing a doorbe
Expresses near-certainty based on clear evidence — for example, hearing a doorbell and concluding a guest has arrived, or seeing wet ground and deciding it rained.
The kitchen light is on, so Mateo must be home by now.
must + base verb — logical conclusion from visible evidence
You have been walking all day — your feet must hurt.
This must be the right house because the address matches exactly.
There must be a mistake — I ordered a small coffee, not a large one.
The ground is wet, so it must have rained while we were asleep.
- have to
can express certainty: 'That has to be the right answer.'
- be bound to
slightly more formal; emphasises inevitability: 'She is bound to be tired after the trip.'
- can only be
used when only one explanation fits: 'It can only be him.'
- cannot / can't
the logical negative — expresses certainty that something is NOT true
文法句型
must + base verb (present deduction)
must have + past participle (past deduction)
must be + adjective/noun
用法筆記
For past deduction, use 'must have + past participle' (e.g., 'She must have left the key on the table'). The negative of this sense is 'cannot / can't + base verb' or 'cannot / can't have + past participle' (e.g., 'He cannot be at work — his car is still in the driveway'), NOT 'must not', which expresses prohibition, not logical impossibility.
常見錯誤
must — noun
1. something that is so important or useful that you cannot do without it in a part
something that is so important or useful that you cannot do without it in a particular situation — for example, a raincoat for a trip to London, or a smartphone for a modern office worker.
A warm coat is an absolute must if you move to Canada.
absolute must — strong intensifier collocation
For serious photographers, a sturdy tripod is a must.
a must for [person] — typical pattern
Comfortable walking shoes are a must when exploring old cities.
A good dictionary is a must for anyone learning a new language.
- essential
more formal; can be used as both adjective and noun: 'warm clothes are essential'
- necessity
more formal; 'a necessity' feels stronger and more serious than 'a must'
- requirement
implies an official rule rather than personal need
文法句型
a must
an absolute must
a must for [person/purpose]
用法筆記
This noun is always used in the singular with the indefinite article 'a'. It is especially common in travel guides, product reviews, and advice articles. 'Absolute must' is a frequent intensifier.
常見錯誤
must — prefix
1. used in front of a verb to form a compound adjective or noun that describes some
used in front of a verb to form a compound adjective or noun that describes something so good that people should definitely experience, own, or use it — for example, a must-see film, a must-read book, or a must-have gadget.
This documentary about coral reefs is a must-see for divers.
must-see — most common compound
The new novel by Haruki Murakami is a must-read for literary fans.
must-read — common compound
A portable power bank is a must-have item for long flights.
The night market is a must-visit destination for food lovers.
- essential
more formal; can replace most must- compounds: 'essential reading', 'essential viewing'
- unmissable
common in entertainment reviews; similar in meaning to 'must-see'
文法句型
must-verb (must-see, must-read, must-have, must-visit)
用法筆記
Compounds formed with must- are written with a hyphen between 'must' and the verb. They function like nouns (e.g., 'This film is a must-see') or adjectives placed before a noun (e.g., 'a must-read book'). The most productive patterns are must-see, must-read, must-have, and must-visit.