“不雨则已，一雨倾盆”，形容坏事不来则已，一来则不止。It never rains but it pours 和中国成语里的“祸不单行”意思一样。

例句

We had nothing to do for weeks, then suddenly we have all this work to do; it never rains but it pours!

I missed my train this morning, lost my wallet and spilt coffee all over myself; it never rains but it pours.

请注意

如果你给某人的计划或建议“泼冷水” pour cold water, 那就表示你的态度是太过苛刻或消极。

例句

I wanted to walk up the mountain but Jane threw cold water on the idea by taking the cable car.