water under the bridge
US /ˈwɔtər ˈʌndər ðə brɪdʒ/
UK /ˈwɔtər ˈʌndər ðə brɪdʒ/

1.
过眼云烟, 过去的事
past events or issues that are no longer important or relevant, and should be forgotten
:
•
Their old argument is just water under the bridge now; they've moved on.
他们过去的争吵现在只是过眼云烟;他们已经翻篇了。
•
I know we had some disagreements, but that's all water under the bridge.
我知道我们有过一些分歧,但那都已经是过去的事了。