白费气力 meaning in English

waste one's effort on; draw water with a sieve; pour water into a sieve; catch at shadows; plough the sands; go on a wild goose chase; beat the air

Anyway, they won't have a cold coal to blow at .
无论如何他们不会干白费气力的事。
The enemy officer tried to sort his men out , but in vain
敌军官试图将其部下整顿一番，但结果是白费气力。
But if there had been no stony obstruction there the labor would have been useless still , for if the beam had been wholly cut away injun joe could not have squeezed his body under the door , and he knew it
就算没有石头，印第安乔也是白费气力，他可以砍断大横木，但要想从门下面钻出来也是不可能的，他自己也明白这一点。