一…就
Pattern
一 + action / event, 就 + result
Key words
Core idea
一…就 links two events so the second happens immediately after the first. The first part sets the trigger. The 就 part gives the result or next action.
This pattern is useful when English would say “as soon as.”
Usage boundary
The first event does not need to be long. It is often a short action or a moment of arrival, seeing, hearing, or finishing.
Do not move 就 to the end of the sentence. It belongs before the result or next action.
Examples
我一到家，就给你打电话。
Wǒ yí dào jiā, jiù gěi nǐ dǎ diànhuà.
As soon as I get home, I will call you.
她一看见老师，就笑了。
Tā yí kànjiàn lǎoshī, jiù xiào le.
As soon as she saw the teacher, she smiled.
我们一下课，就去吃饭。
Wǒmen yí xiàkè, jiù qù chīfàn.
As soon as class ends, we go eat.
Common mistakes
Avoid
我一到家，给你电话就。
Use
我一到家，就给你打电话。
就 comes before the result or next action, not after the whole clause.