HSK 5
除非⋯⋯，否则/不然⋯⋯
chú fēi ⋯ ⋯ ， fǒu zé / bù rán ⋯ ⋯
Unless..., otherwise...
Explanation
除非……，否则/不然…… (chúfēi……, fǒuzé / bùrán……) is a compound sentence indicating a condition (a sentence with two or more clauses joined by conjunctions). It means "Unless..., otherwise...": only when the sole condition in the 除非 clause is met can the bad consequence stated in the 否则/不然 clause be avoided.
除非 (chúfēi = unless) + the sole condition，否则 (fǒuzé) / 不然 (bùrán) — both meaning "otherwise" + the consequence. 否则 leans toward written usage, 不然 toward colloquial speech.
When you want to emphasize that there is only ONE way to avoid an undesirable result, carrying a nuance of warning or of setting a mandatory condition.
除非 can be replaced by 只有 (zhǐyǒu = only if) in some contexts, but 只有 goes with 才 (cái) and not with 否则; do not mix them up.
Vietnamese learners often pair them wrongly, using 除非...才... and then adding 否则; remember: 除非 goes with 否则/不然, while 只有 goes with 才.
Examples
Unless we go by plane, otherwise we will surely be too late.
Unless you check carefully, otherwise it is all too easy to make mistakes.
Practice
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Learn “除非⋯⋯，否则/不然⋯⋯” effectively
The grammar point “除非⋯⋯，否则/不然⋯⋯” (Unless..., otherwise...) is one of the key structures at HSK 5. To use it fluently, you need to understand the contexts where it's used and practice regularly.
Study tip: read the examples aloud many times to build a natural reflex. Then try making your own sentences for your own situations. Use the audio button to hear and practice accurate pronunciation.
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