A：昨天下午三点我给你打电话的时候,你正在做什么?
What were you doing when I called you at three o'clock yesterday afternoon.
B：我正在游泳.
I was swimming.
A：我打电话的时候,汤姆正在做什么?
What was Tom doing when I called?
B：他正在踢足球.
He was playing football.
A：那玛丽正在做什么呢?
What about Mary?
B：她正在做作业.
She was doing her homework.
A：你们都很忙啊!
You were all very busy.