除非……，否则……
Reach for 除非...否则... when you need to lay out the one exception that would change the default outcome — 'unless X happens, otherwise Y.' It's the language of ultimatums, contracts, and policy: the 除非 clause names the single escape condition, and the 否则 clause states what happens if that condition isn't met. The default outcome continues; only the named exception can override it.
Structure
除非 [EXCEPTION CONDITION]，否则 [DEFAULT RESULT]
chúfēi... fǒuzé...
How to Think About It
除非 is a closed door with a key. The 除非 clause is the only key that opens an alternative outcome; everything else leads to the 否则 result. That's why it's stronger than 如果不: 如果不 lists one negative condition among many, while 除非 says this is the single carve-out. Pair it with 否则 (not 就) to keep the contrast sharp.
Examples
除非你提前通知我，否则我不会去。
Chúfēi nǐ tíqián tōngzhī wǒ, fǒuzé wǒ bú huì qù.
Unless you notify me in advance, I won't go.
除非有特殊情况，否则会议必须按时召开。
Chúfēi yǒu tèshū qíngkuàng, fǒuzé huìyì bìxū ànshí zhàokāi.
Unless there are special circumstances, the meeting must be held on time.
除非下大雨，否则比赛照常进行。
Chúfēi xià dàyǔ, fǒuzé bǐsài zhàocháng jìnxíng.
Unless it rains heavily, the game will go ahead as usual.
Common Mistake
Learners often pair 除非 with 才 to mean 'only then,' which works for the positive flip but confuses the two structures. The pair 除非...否则... requires 否则 to introduce the default; using 就 or 才 produces an unidiomatic mash-up.
除非你道歉，就我原谅你。
除非你道歉，否则我不会原谅你。
Don't Confuse With
除非……，才……
除非...才... = 'only if X happens will Y happen,' positive framing. 除非...否则... = 'unless X, then negative Y,' negative framing. Pick based on whether you're stating the carve-out or the consequence of missing it.
如果不……，就……
Weaker, more conversational version. Use it for everyday conditionals; reach for 除非...否则... when you want the absoluteness of an ultimatum.
要不然……
要不然 means 'otherwise...' as a standalone connector. It can replace 否则 in casual speech, but 除非 still introduces the exception.
Practice
Fill in the blank: ___你努力学习，否则考试很难通过。
Show answer
除非
Fill in the blank: 除非他亲自来，___我不签字。
Show answer
否则
Arrange: 否则 / 除非 / 不能 / 你 / 进 / 有 / 你 / 邀请函
Show answer
除非你有邀请函，否则你不能进。
Translate to Chinese: Unless the boss approves, otherwise we can't change the plan.
Show answer
除非老板批准，否则我们不能改变计划。
Use 除非...否则... to set one condition that would change a decision you've already made.
Show answer
除非公司给我加薪，否则我打算明年辞职。
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: