HSK 5
一旦 V
yīdàn V
once
Structure
一旦 + Condition / Action, (就/便) + Result
How it works
The word '一旦' is a conjunction used to indicate an assumed condition. It means 'once' or 'in case,' suggesting that as soon as something happens, a specific result or change will follow, often emphasizing an irreversible or significant outcome.
Examples
这种机会一旦错过，就很难再有了。
Zhèzhǒng jīhuì yīdàn cuòguò, jiù hěn nán zài yǒule.
Once this kind of opportunity is missed, it will be hard to have it again.
信誉一旦失去，就无法重新建立。
Xìnyù yīdàn shīqù, jiù wúfǎ chóngxīn jiànlì.
Once credit is lost, it is impossible to rebuild.
计划一旦确定，请不要随意更改。
Jìhuà yīdàn quèdìng, qǐng bùyào suíyì gēnggǎi.
Once the plan is confirmed, please do not change it at will.
Common mistakes
Forgetting to use the adverb '就' or '便' in the second clause to connect the result, which makes the sentence sound incomplete.
Tip
Think of '一旦' as focusing on a critical turning point; it is often used for things that are difficult to change back once they start.
More HSK 5 grammar
See 一旦 V in real Chinese
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