一经…便…
as soon as …: once a formal step happens, the result follows
Structure
一经 动词（发现／录取／批准） ， 便／就 结果
What it means
As soon as …: once a formal step happens (found, accepted, approved), a fixed result follows.
How it is built
(Subject) + 一经 + verb，便／就 + result: 商品一经售出，概不退换 (Goods once sold cannot be returned). Typical verbs: 发现, 录取, 批准, 售出, 查实.
When to use it
Written; common in rules and notices. 便 is the written 就, and it is often dropped before another adverb (概, 一律). The everyday version is 一…就….
Watch out
Not for casual actions: ✗ 我一经到家便睡觉 ✓ 我一到家就睡觉. The step after 一经 is formal or official, like being found or approved.
Examples
考生一经录取，便可以进入官场。
Once accepted, a candidate could enter officialdom.
商品一经售出，概不退换。
Goods once sold cannot be returned or exchanged.
Learn this in Lesson 78 · HSK 6–7: 科举制度 (The imperial examinations)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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