Must / cannot but (非…不可)

Structure 非 + verb/clause + 不可 / 不行 / 不成

非…不可 (fēi… bùkě) is a double negative expressing inescapable necessity: "there's no choice but to…, it absolutely must…". 这件事非你去办不可 = "this matter must be handled by you and no one else"; 想成功，非下苦功不可 = "to succeed, you simply have to put in hard graft". The closing varies: 不可 (neutral and most common), 不行 and 不成 (more colloquial). Sometimes 非 also marks stubborn determination: 他非去不可 = "he's dead set on going".

Examples

这zhè件jiàn事shì非fēi你nǐ去qù办bàn不bù可kě，别bié人rén都dōu不bù行xíng。
This matter must be handled by you and no one else.
想xiǎng要yào成chéng功gōng，非fēi下xià一yī番fān苦kǔ功gōng不bù可kě。
If you want to succeed, you simply have to put in real hard work.
他tā认rèn定dìng的de事shì，非fēi做zuò到dào底dǐ不bù成chéng。
Once he sets his mind on something, he has to see it through to the end.
再zài晚wǎn就jiù赶gǎn不bù上shàng车chē了le，现xiàn在zài非fēi走zǒu不bù行xíng。
Any later and we'll miss the train; we have to leave right now.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.