生米熟饭

lit. the raw rice is now cooked (idiom); fig. it is done and can't be changed; It's too late to change anything now.

the rice is cooked; what's done is done

lit. the rice has already been cooked (idiom); fig. what is done cannot be undone

lit. the timber has been turned into a boat already (idiom); fig. what is done cannot be undone