As the saying goes — it's no use crying over spilt milk.

常言道：覆水难收，后悔也于事无补。

《牛津词典》

Now it's done, regrets are of no avail.; It's no use crying over spilt milk.

事已如此， 后悔也是枉然。

《新英汉大辞典》

It is no use crying over spilt milk.

打翻牛奶，哭也没用；覆水难收。

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