必须
must; have to
bìxū
What does 必须 mean?
必须 (bìxū) is the adverb 'must / have to,' expressing obligation or necessity that comes from rules, logic, or strong personal resolve. It is placed before the verb: 你必须去 (you must go), 我们必须准时 (we must be on time). Two key differences from English 'must': first, 必须 carries a tone of external requirement or firm necessity — for softer 'should' use 应该 (yīnggāi), and for casual 'gotta' use 得 (děi); second, the negative is NOT 不必须.
To say 'don't have to,' use 不必 (bùbì) or 不用 (búyòng); to say 'must not,' use 不能 (bùnéng) or 不可以 (bù kěyǐ). 必须 itself stays in the affirmative. It is common in signs, regulations, and any context where the speaker wants the obligation to sound firm.
Character breakdown
must; certainly; necessarily
must; necessary; ought to
Memory hook: Two 'must' characters in a row — necessity doubled.
Example sentences
明天的会议你必须参加。
Míngtiān de huìyì nǐ bìxū cānjiā.
You must attend tomorrow's meeting.
neutral
学生必须按时交作业。
Xuéshēng bìxū ànshí jiāo zuòyè.
Students must hand in their homework on time.
written
我们必须六点之前到机场。
Wǒmen bìxū liù diǎn zhīqián dào jīchǎng.
We have to get to the airport before six.
neutral
想学好中文，就必须多说多练。
Xiǎng xué hǎo Zhōngwén, jiù bìxū duō shuō duō liàn.
If you want to master Chinese, you have to speak and practice a lot.
neutral
Common phrases with 必须
Synonyms
Don't confuse 必须 with
必要 is an adjective/noun meaning 'necessary / necessity' — 没有必要 (there's no need). 必须 is the adverb 'must' that goes before a verb. Don't say 必要去 — say 必须去 or 有必要去.
必然 means 'inevitable / inevitably' — about logical certainty, not obligation. 必然结果 (inevitable result) is different from 必须做 (must do).
不必 is the negation pair — 'don't have to / no need to.' Beginners often write