無益的英文：
profitless; useless; fruitless; barren; vain; futile; unprofitable; no good; without benefit; all for naught

profitless是什么意思：
a. 无利益的,无益的,浪费的

Revising the procedure was an entirely profitless exercise.
对程序进行修改是徒劳无功的.

Of course Sun fully expects its profitless approach to turn a profit in the end
当然，Sun公司完全期望其无利可图方式最终会变得有利可图。

The poor ballet dancer must devote years of incessant toil to her profitless task before she can shine in it
可怜的芭蕾舞演员必须把多年不断的辛劳献给她无益的苦差事，之后她才能在芭蕾上大放异彩。

useless是什么意思：
adj. 无用的；无效的；差劲的，不行的

A well devoid of water is useless.
无水的井没有用途。

Damn this useless typewriter!
这个破打字机真该死!

A car is useless without petrol.
A car is useless without petrol.

fruitless是什么意思：
adj. 无成果的，徒劳的；不结果实的

It was a fruitless search.
搜寻工作毫无结果。

So far the search for the missing boy has been fruitless.
到目前为止，还没有找到那失踪的男孩。

The years roll by—spend one’s life in fruitless efforts
岁月蹉跎