must

/məst/ (bre, ipa) · [mˈʌst] /məst/ (ame, ipa) · /mʌst/ (bre, ipa) · [mˈʌst] /mʌst/ (ame, ipa) · [mˈʌst] /məs(t), ˈməst/ (ame, mw)

must — 情態動詞

1. shows that a rule, a need, or the situation makes an action necessary now or in

1.情態動詞A2
釋義

必須

表示規定、必要或不能不做

shows that a rule, a need, or the situation makes an action necessary now or in the future.

例句

Passengers must show their passports at the airport gate.

乘客在機場登機門必須出示護照。

must + base verb for rule

Karim must wear gloves before he touches the lab bottles.

Karim 碰實驗室瓶子前，必須先戴上手套。

同義詞
  • have to

    often points more clearly to an outside rule or situation

  • need to

    usually sounds less forceful and more practical than 'must'

文法句型

must + base verb

must not + base verb

Must + subject + base verb?

用法筆記

Use this sense for rules, official instructions, and situations where there is no real choice. For past necessity, English usually uses 'had to', not 'must'.

常見錯誤

❌Yesterday I must finish the report.
✅Yesterday I had to finish the report.
💡use 'had to' for a past obligation.

2. shows that the speaker has firmly decided to do something soon.

2.情態動詞B1
釋義

一定要

表示自己下定決心要去做

shows that the speaker has firmly decided to do something soon.

例句

I must call Brooke tonight and explain the whole mistake.

我今晚一定要打電話給 Brooke，把整件錯事解釋清楚。

must + verb for strong personal resolve

We must book the train before the cheap tickets disappear.

我們一定要先把火車票訂好，不然便宜票會賣完。

同義詞

文法句型

must + base verb

用法筆記

This sense usually reports the speaker's own resolve or a plan they feel strongly about. Distinguish it from sense 1, which points to rules or outside necessity.

3. appears in set phrases such as 'I must say' to make a comment sound more forcefu

3.情態動詞B1
釋義

說真的

放在 say、admit 等前面加強語氣

appears in set phrases such as 'I must say' to make a comment sound more forceful or more frank.

例句

I must say, Hana handled the angry customer very calmly.

說真的，Hana 面對生氣客人時處理得很冷靜。

fixed phrase: I must say

We must admit, the tiny cafe served excellent noodles.

我們得承認，那家小咖啡店的麵真的很好吃。

fixed phrase: must admit

同義詞
  • frankly

    a direct adverb that can introduce an opinion in a similar way

  • honestly

    often adds a tone of plain or sincere comment

文法句型

I must say, ...

I must admit, ...

I must confess, ...

用法筆記

The phrase adds emphasis or honesty before a remark. It does not mean the speaker is under a duty; it is most common with say, admit, confess, and tell.

常見錯誤

❌I must say, the soup is lovely' means the speaker had no choice but to speak.
✅Here 'must' only strengthens the opinion.
💡this set phrase adds emphasis, not obligation.

4. used to tell someone that an experience or action is so good that they should no

4.情態動詞B1
釋義

別錯過

表示某件事很值得去做或體驗

used to tell someone that an experience or action is so good that they should not miss it.

例句

You must try Dario's tomato soup before the cafe closes.

那家咖啡店打烊前，你可別錯過 Dario 的番茄湯。

must try for strong recommendation

You must visit the night market when you are in Tainan.

你人在 Tainan 的時候，可別錯過那座夜市。

同義詞
  • should

    gives milder advice than 'must'

  • ought to

    similar in meaning but usually sounds a little more formal

文法句型

must + base verb

用法筆記

Unlike sense 1, this is friendly advice, not a command. It often appears with food, places, books, films, or events the speaker thinks the listener will enjoy.

常見錯誤

❌Employees must try the soup before work.
✅Employees have to try the soup before work.
💡if it is a rule, use the obligation sense instead of this recommendation sense.

5. shows that you think something is almost certainly true because the evidence poi

5.情態動詞B2
釋義

想必；一定

根據跡象推斷事情幾乎可以確定

shows that you think something is almost certainly true because the evidence points that way.

例句

The kitchen lights are on, so Dario must be home already.

廚房的燈亮著，Dario 想必已經在家了。

must be + complement for deduction

Saira left at dawn, so she must have reached Taipei by now.

Saira 天一亮就出發了，現在一定已經到 Taipei 了。

must have + past participle

同義詞
  • be bound to

    also suggests strong certainty, often about what is likely to happen

  • surely

    an adverb that can mark a similar confident conclusion

文法句型

must be + complement

must have + past participle

用法筆記

Here the speaker is making a strong guess from evidence, not telling anyone what to do. Distinguish it from sense 1, which gives obligation rather than logical conclusion.

常見錯誤

❌It must maybe rain later.
✅It may rain later.
💡'must' shows strong certainty, not a weak possibility.

must — 名詞