water under the bridge
过去的事情；已经发生的无法改变的事情
口语·表示释怀或放下过去
英文释义
something that happened in the past and is no longer important or relevant
例句
We had a fight last year, but it's all water under the bridge now.
典故来源
源自水流过桥下后一去不返的意象，比喻过去的事不再重要。