徒劳无益的用英语怎么说？

徒劳无益的

例句

• It's all to no purpose; I tell you that you are plowing the sand. 这是徒劳无益的; 告诉你,你在枉费心机.
• What troubled him most was the uselessness of Fanny's effort. 他想的最多的还是范妮在绘画上徒劳无益的努力.
• The years of ineffectual service count big in the bestowal of rewards. 几年徒劳无益的服务,在论功行赏时就大有关系.