It is useless to speculate why he did it.

对他为什么这么做妄加猜测毫无用处。

《牛津词典》

It is useless to flog a dead horse.

鞭死马无益；勿旧调重弹。

youdao

But it is useless to look for sympathy in this world.

但是在这个世道寻求同情是没用的。

youdao

Milton explains that the Licensing Order of 1643 is ineffective, it's useless because, and I'm quoting here, " order avails nothing to the suppressing of scandalous, seditious, and libellous books, which were mainly intended to be suppressed."

弥尔顿解释说《出版管制法》毫无作用，一无是处，我引用他的话说原因“,因为这个管制法对控制诽谤性的，有煽动性的，中伤他人的需要被控制的书籍毫无用处“

耶鲁公开课 - 弥尔顿课程节选

As for recycling, it is useless to urge people to salvage stuff for which there are no buyers.

ECONOMIST: Talking rubbish

It is useless to discuss or to consider a no-fly zone unless you are thinking beyond it, unless you are already then starting to plan.

CNN: Mortar shells hit Damascus college; deaths reported

It is useless to try to influence either school of thought since they are well entrenched in their beliefs, so let me write this for us old timers who have seen enough uncertainty, broken promises and false projections to choose skepticism over hope.

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