Earnestly, actively, or closely at work.

勤于工作的；忙碌的。

Bustling; full of activities.

热闹的事务；繁忙的。

In use, as a telephone line.

【美】正在使用的(如电话线路的)。

Meddlesome.

好管闲事的。

To keep constantly engaged; occupy.

孜孜不倦地做事；使忙碌。

Busy means keeping earnestly and actively at work.

Busy 指专心勤勉于工作。

It also describes one who has much to do. Sometimes it carries the sense of occupied.

又指人事务繁忙或没有时间：

Diligent describes one who is carefully and busily engaged in following some pursuit.

Diligent 指人小心翼翼忙于研究、学业等：

Industrious describes one who is habitually busy and applies himself closely.

Industrious 指人经常很忙专心于工作：