过去进行时的主从复合句

My mother was cooking when I arrived home yesterday.
When the telephone rang,I was writing a letter.
While the driver was looking for customers,he saw a woman.
He was watching TV when suddenly the telephone rang.
They were playing football when it began to rain.
We were watching a wonderful movie on TV when suddenly there was a knock on the door.
While he was waiting at the bus stop,he met his old friend.
While Jack was cleaning his car,he found a suitcase.
What was he doing when you called?
When I arrived home yesterday,my mom was preparing supper.
What were your friends doing when you arrived at school yesterday morning?
What was your family doing when you arrived home yesterday?
While I was doing my homework,the lights went out.
不明白的再问哟,请及时采纳,多谢!