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

1.
過眼雲煙, 過去的事
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.
他們過去的爭吵現在只是過眼雲煙;他們已經翻篇了。
•
I know we had some disagreements, but that's all water under the bridge.
我知道我們有過一些分歧,但那都已經是過去的事了。