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置於句首，句子必須用倒裝結構：
hardly / scarcely had i got home when it began to rain.
no sooner had i got home than it began to rain.