［状语从句］表示"一…就…"的结构

hardly/scarcely…when/before， no sooner…than　和as soon as都可以表示"一…就…"的意思。例如：

　　I had hardly / scarcely got home when it began to rain. 刚回家，就下起雨来了。

　　I had no sooner got home than it began to rain.

　　As soon as I got home， it began to rain.

　　注意：如果hardly， scarcely 或no sooner置于句首，句子必须用倒装结构。例如：

　　Hardly / Scarcely had I got home when it began to rain.

　　No sooner had I got home than it began to rain.