to flog a dead horse
01
to waste time and energy on something that cannot be changed or revived
Dialect
British
British![to [flog] a dead horse definition and meaning](https://cdn.langeek.co/photo/40835/original/?type=jpeg "to [flog] a dead horse definition and meaning")
例
Arguing with him about his decision now is just flogging a dead horse—he's made up his mind.
to waste time and energy on something that cannot be changed or revived
British
