waste one's breath/words
speak pointlessly;speak or argue with no result白费唇舌
The old man is so stubborn that you'd be only wasting your breath trying to make him change his mind.那个老头子太固执,你去劝他改变主意,不过是白费口舌。
I saw that I was wasting my words;he refused to believe me.我发现我是在白费口舌,他根本不相信我。
Don't argue with Frank any longer.You are only wasting your breath trying to get him to contribute to the Red Cross.不要与弗兰克再争下去了,你要他给红十字会捐款只不过是白费口舌而已。