HSK 2 grammar · preposition
当
当 — when / at (the time of)
Pattern
+ +
+ +
( ) can be left out · other words may come before, between and after
How it works
当 introduces the time an action happens, usually paired with 的时候 (or 时) at the end — "when …". It opens the sentence and sets the time frame for what follows.
Examples
当我回家的时候，天黑了。
Dāng wǒ huí jiā de shíhou, tiān hēi le.
When I got home, it was dark.
当他说话时，大家都听。
Dāng tā shuōhuà shí, dàjiā dōu tīng.
When he speaks, everyone listens.
当你需要帮助的时候，给我打电话。
Dāng nǐ xūyào bāngzhù de shíhou, gěi wǒ dǎ diànhuà.
When you need help, call me.
Related
See it in a story
In the app, 当 is underlined wherever it appears in the stories you read, and practised with sentences from them. Free.