放弃
close the book on sth
(因相信不会成功或没有结论而)放弃
to stop doing sth because you no longer believe you will be successful or will find a solution
The police have closed the book on the case (= they have stopped trying to solve it).警方已经放弃侦破此案。
释义来自《牛津高阶英汉双解词典》第 9 版