a done deal

US /ə dʌn diːl/
UK /ə dʌn diːl/
"a done deal" picture
1.

板上釘釘的事, 已成定局

a final agreement or decision that cannot be changed

:
The contract is signed, so it's a done deal.
合同已簽署,所以這是板上釘釘的事
Don't worry, the merger is a done deal; the announcement will be made next week.
別擔心,合併已經是板上釘釘的事了;下週就會公布。