单词beat a dead horse
网络: 白费口舌；白费力气；炒冷饭
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。