busy

The doctor is too busy with patients to take your call right now.

(Chinese) 医生正忙于诊治病人，现在不能接听你的电话。

Monday is usually a busy day at the post office.

(Chinese) 周一通常是邮局非常繁忙的一天。

I tried to call the customer service, but the line was busy.

(Chinese) 我试着拨打客服电话，但线路一直占线。

You will hear a busy signal if you call someone who is already talking.

(Chinese) 如果你给正在通话的人打电话，你会听到占线音。