hardly/scarcely…when/before, no sooner…than　和as soon as都可以表示"一…就…"的意思，例：
    I had hardly / scarcely got home when it began to rain.
    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，句子必須用倒裝結(jié)構(gòu)：
    Hardly / Scarcely had I got home when it began to rain.
    No sooner had I got home than it began to rain.