HSK 5
除非...否则... (chúfēi...fǒuzé) in Chinese
除非...否则/不然... states an exception and then gives the consequence that holds if that exception is not met. 除非 introduces the only escape or required exception; 否则 or 不然 means otherwise. Unlike 除非...才..., this frame describes the consequence of failing the condition rather than the result enabled by meeting it.
STRUCTURE
除非 + Exception, 否则/不然 + Result
When to use 除非…否则/不然… — and when not
Use it when
- To state an exception to a negative consequence: 除非现在出发，否则会迟到。
- To give a requirement and warning: 除非本人同意，不然不能公开。
- With the exception after the main warning in speech: 我们会迟到，除非现在就走。
Don't use it when
- Do not use 否则 to state the result that follows when the 除非 condition is met; use 才 for that relation.
- Do not stack 除非 and 否则 before the exception clause.
- Do not assume 除非 must always be sentence-initial; a postposed exception can be grammatical.
Right vs. wrong
除非否则现在出发，我们会迟到。
除非现在出发，否则我们会迟到。
除非 and 否则 are stacked before the exception
除非 introduces the exception 现在出发, while 否则 introduces the consequence if that exception is not met.
除非现在出发，我们否则会迟到。
除非现在出发，否则我们会迟到。
否则 is placed after the consequence-clause subject
As a connector meaning 'otherwise,' 否则 comes before the consequence clause and its subject in this sentence.
Examples
除非现在出发，否则我们会迟到。
Chúfēi xiànzài chūfā, fǒuzé wǒmen huì chídào.
Unless we leave now, we will be late.
除非本人同意，不然不能公开这份材料。
Chúfēi běnrén tóngyì, bùrán bù néng gōngkāi zhè fèn cáiliào.
Unless the person agrees, this material cannot be made public.
我们会迟到，除非现在就走。
Wǒmen huì chídào, chúfēi xiànzài jiù zǒu.
We will be late unless we leave right now.
Common mistakes
除非否则现在出发，我们会迟到。
Chúfēi fǒuzé xiànzài chūfā, wǒmen huì chídào.
Separate the exception and consequence markers: 除非现在出发，否则我们会迟到。
除非现在出发，我们否则会迟到。
Chúfēi xiànzài chūfā, wǒmen fǒuzé huì chídào.
Put 否则 before the consequence clause: 否则我们会迟到。
Think you've got it?
Write your own 除非…否则/不然… sentence and check that grammar point first.
除非...否则... (chúfēi...fǒuzé) FAQ
What is the difference between 除非...否则... and 除非...才...?
除非 P，否则 Q gives the consequence when P is not met. 除非 P，才 R states that P is required for R. The two frames look at opposite sides of the same condition.
Can 除非 come at the end of a sentence?
Yes. A postposed exception such as 我不会改变计划，除非天气恶化 is grammatical. Do not reject it solely because 除非 is not sentence-initial.