图：来自Pexels平台的asim alnamat摄影作品
“板上钉钉”，是汉语中的成语，直译为在木板上敲定铁钉的情境，它寓意事情已如板上钉下的钉子，即刻稳固无变，类似于已成定局或已成事实的境况。这个成语与英文中常用的“cast in stone”含义相近，表达出“彻底确定、无法更改”的意味。
示例句子：
讨论仍在继续，但他的想法尚处在初始阶段，未至“板上钉钉”的程度。
In the midst of the discussion, his idea is still in its early stages and not yet cast in stone.
他提出了一个建议，但事情尚未定论，尚未板上钉钉。
He has made a suggestion, but the matter is not yet finalized or cast in stone.
尽管我非常愿意参加，但我必须去出差。并且，我已明白这个日期如板上钉钉般无法更改。
Although I would really like to attend, I have to go on a business trip. And I understand that the date is set in stone and cannot be changed.