beating a dead horse造句

• Quit asking him to do you a favor . you ’ re beating a dead horse
  别再求他帮你忙了，你这是白费劲。
• I've already made up my mind . there's no sense beating a dead horse
  我已经下了决心，不要再白费口舌了。
• "it is not my predilection to go beating a dead horse . . . but i have little pity for a cannibal .
  我没兴趣对死人出手...但是我也不会同情吃人的家伙。