They were hard at it with brooms and mops.

他们忙着用扫帚和拖把打扫卫生。

I am hard at it.

我努力工作。

They were hard at it with brooms and mops .

他们忙着用扫帚和拖把打扫卫生。

Me, too. I've worked hard at it for a whole week.

王俊峰：我也是。整个星期我都在努力学习英语。

In order to master English we must work hard at it.

为了掌握英语，我们必须努力学习它。

Whether The pay depends on whether you will work hard at it.

工资依你是否努力工作而定。

Some people dream of success…While others wake up and work hard at it.

有些人梦想飞黄腾达，有些人则是在梦醒之后为此努力拼搏。

The policemen were already hard at it when we reached the scene of the accident.

当我们到达肇事地点时，警察们已经在哪里忙开了。

Some people dream of success… while others wake up and work hard at it. ~Mark Zuckerberg.

很多人梦想成功，而一些人却醒来为之努力工作。

We're still working hard at it. We've got a lot of a good team of people working up there.

我们还在努力。我们有很多很好的、为之努力的团队。