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.