「白費力氣或徒勞無益」用英語表達可以是 flog a dead horse 或 beat a dead horse，寓意：
1、waste energy on something that has no chance of succeeding
把精力浪費在沒有成功機會的事情上
2、wasteefforton a lost cause
在失敗的事業上浪費精力
3、engaging in a fruitless effort
徒勞無功
4、attempting to revive interest in something which has died out
試圖恢復人們對已經消失的東西的興趣
解析：短語動詞 die out 譯為「消失，滅絕」。
例如：
1、He keeps trying to get his manuscripts published, but I think he is flogging a dead horse.
他一直想讓他的手稿出版，但我認為他是白費力氣。
解析：get something done 是一種使役結構，表示「讓某人幫我們做某事」。
2、There's no use trying to keep this business going. We are flogging a dead horse.
想讓這件事繼續下去是沒有用的。我們白費力氣。
解析：no 作限定詞，用在一個詞名詞或名詞短語之前，no 與名詞之間沒有冠詞，相當於 not any 或 not a/an.
3、I've told him numerous times to manage his routineeffectively, but I think I've just been flogging a dead horse.
我已經告訴他很多次了，要有效地管理他的日常事務，但我想我只是在鞭打一匹死馬。
解析：
a、現在完成進行時 have been floggiing a dead horse 表示動作從過去一直持續進行到現在。
b、time 譯為「次，回」的時候，是可數名詞。
4、You're flogging a dead horse trying to persuade him to come with us. He hates going out at night.
你想說服他和我們一起去，真是白費力氣。他討厭晚上出去。
解析：現在分詞短語 trying to persuade hime to come with us 作狀語表伴隨。
5、You keep trying to convince him to join your company,butI think you're flogging a dead horse. He's happy where he is.
你一直想說服他加入你的公司，但我認為你是白費力氣。他在那裡很開心。