set in stone
成語所屬單字stone
set in stone — 慣用語
1. completely fixed and impossible to change; used especially when talking about pl
1.慣用語
釋義
一成不變；無法更改
completely fixed and impossible to change; used especially when talking about plans, rules, or decisions
例句
The wedding date is not set in stone yet, so we can still change it if needed.
These guidelines are not set in stone and can be adjusted as the project develops.