Advanced Structure 一…就… (yī... jiù...): As soon as... / Whenever...

Pattern

• (Subject) + 一 + Verb 1，(Subject) + 就 + Verb 2

Usage

• At HSK 4, the structure 一…就… expands into three main uses: (1) immediate sequence of two actions (e.g., 他一回到家就开始做饭 — "As soon as he got home, he started cooking"); (2) habitual condition and automatic reaction ("whenever", e.g., 他一紧张就脸红 — "Whenever he gets nervous, he blushes"); and (3) minimal effort leading immediately to a result (e.g., 这本书我一看就懂了 — "I understood this book at a single glance").
• The two clauses may share the same subject (placed before 一) or have different subjects.
• Both 一 and 就 must be followed by verbs or verb phrases, never nouns.

Examples

1. 1

   他一回到家就开始做饭。

   Tā yī huídào jiā jiù kāishǐ zuòfàn.

   As soon as he got home, he started cooking.

2. 2

   这本书我一看就懂了。

   Zhè běn shū wǒ yī kàn jiù dǒng le.

   I understood this book as soon as I read it.

3. 3

   他一紧张就脸红。

   Tā yī jǐnzhāng jiù liǎn hóng.

   Whenever he gets nervous, his face turns red.