徒劳无功; 炒冷饭; 白费口舌; 浪费精力

白费口舌；徒劳；在已经失去意义的问题上白花力气

flog a dead horse───徒劳；白费力

to flog a dead horse───徒劳无功；枉费心机

eat like a horse───吃得多

dead horse───预付的工资；旧债；无益的事

set a deadline───规定最后期限

a Trojan horse───特洛伊木马

a dead loss───绝对的损失

beat the disease───战胜疾病

dead horses───预付的工资；旧债；无益的事

I hate to beat a dead horse, but it is very important that you understand this before you leave.───我不想多此一举，但你离开以前必须了解这个。

Oh, Come on. Let's not beat a dead horse.───算了，别再白费口舌了。