Definition
This idiom is used to convey that a past event cannot be altered or undone.
木已成舟
I know you're disappointed with the outcome, but what's done is done, and we need to move forward.
我知道你對結果感到失望，但木已成舟，我們需要向前看。
He made a mistake, but what's done is done, all we can do is learn from it.
他犯了錯誤，但木已成舟，我們能做的就是從中學習。
Although I wish I could change the past, what's done is done, and I have to accept it.
雖然我希望可以改變過去，但木已成舟，我必須接受它。