一…就…yī...jiù...

Correlative Structure 一…就… (yī...jiù...) – As Soon As

Meaning: Structure indicating immediate succession of two actions

Pattern

The correlative pattern 一…就… (yī…jiù…) denotes that action two follows action one immediately, leaving virtually no interval.
It translates into English as “as soon as”, “the moment that”, or “whenever”.
It functions flexibly across clauses sharing a single subject (他一回家就睡觉, 'as soon as he gets home he goes to sleep') or having two distinct subjects (下课铃一响，学生们就跑出来了, 'as soon as the bell rang, the students ran out').
When describing habitual tendencies, it conveys regularity: 我一喝咖啡就睡不着 ('Whenever I drink coffee, I can't fall asleep').
Crucially, 一 must precede verb one, and 就 must precede verb two.

1
他一回家就睡觉。
Tā yì huí jiā jiù shuìjiào.
As soon as he gets home, he goes to sleep.
2
我一看见你就高兴。
Wǒ yí kànjiàn nǐ jiù gāoxìng.
As soon as I see you, I feel happy.
3
下课铃一响,学生们就跑出来了。
Xià kè líng yì xiǎng, xuéshēngmen jiù pǎo chūlái le.
As soon as the dismissal bell rang, the students ran out.

•一 precedes verb 1, while 就 precedes verb 2; do not omit 就 in the second clause.

⚠️ Common Mistakes:

•Incorrect: 一就回家睡觉。 → Correct: 一回家就睡觉。 (一 and 就 precede their respective verbs)

•Do not omit 就 in the second clause.

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