dead horse

基本解释

The horse did what the fox asked, and then the fox went to the lion, who had his den not far off, and said, "A dead horse is lying out there.
狐狸跑到獅子住的洞口邊，對獅子說：“獅子大王，有條小路上躺著一匹死馬，我們一同去，你可以作一頓很不錯的午餐來享受哩。”
The man who feeds his horse on Monday and gives him nothing to eat on Tuesday will have a weak horse on Wednesday, a half-dead horse on Thursday, and a dead horse on Friday.
某一個人，在星期一喂養了他的馬，而星期二什麽也沒給馬喫。那麽，到了星期三，這匹馬就虛弱了；到了星期四，就半死不活了；到了星期五，它就喪命了。
Dead horse on battlefield, Gettysburg, Pennsylvania photographed 1863. Civil War Photograph Collection Library of Congress Prints and Photographs Division.
一匹馬的屍躰躺在戰場上，1863年拍攝於賓夕法尼亞州葛底斯堡。

We say this is like beating a dead horse.
Even there, a horse is not really a rigid body, unless it's been dead for a long time.
馬甚至都不是真正的剛躰,除非是死了很長時間了
耶魯公開課 - 基礎物理課程節選

Better, perhaps, to let the dead horse that is Mr Raffarin take another flogging.
ECONOMIST: Chirac shuffles the pack The