hard at it

adj. 勤劳地工作

例句与用法：

I've been hard at it all the morning.

我一上午都在卖力地干。

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。

词形变化：

形容词比较级: harder | 形容词最高级: hardest |