（当）……的时候
when / while …
Structure
（ 当 ） 句子 + 的时候 ，……
What it means
……的时候 means “when / while …”. It closes the “when” part, which comes first: 吃饭的时候 “when (I’m) eating”.
How it is built
(当) + sentence + 的时候, then the main part: 我到北京的时候，正在下雨 (When I arrived in Beijing, it was raining).
When to use it
English puts “when” at the front; Chinese ends the part with 的时候. 当 at the very start is optional and a little more formal, seen more in writing. In formal writing, 时 alone can replace 的时候.
Watch out
Don’t drop 的: ✗ 吃饭时候 ✓ 吃饭的时候. Don’t use 当 alone like English “when”: ✗ 当我到北京，…… ✓ 当我到北京的时候，……
Examples
吃饭的时候，不要看手机。
Don’t look at your phone while you’re eating.
我到北京的时候，正在下雨。
When I arrived in Beijing, it was raining.
当我回到家的时候，大家都在看电视。
When I got home, everyone was watching TV.
Learn this in HSK 2 · Lesson 5: 过春节 (Spring Festival)
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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