Ответ:

1. When I saw Peter, he was repairing the roof of the house.

2. When I arrived at the station, my parents were waiting me.

3. Wnile they were dancing on the floor, the woman stole their bags and coats.

4.When I arrived, the class had already started and the teacher was writing on the blackboard.

5.When Maria arrived,her mother just left so she couldn't talk to her.

6. The old lady wore a brown coat and a dirty bag when she was walking on the street.

7.She was playing the violin outside when a neighbour opened the window and threw some water.

8.Peter looked very busy when I arrived at the office. What did he do?

9.The poy was playing the computer when he heard his father. He immediately opened his book.

10. My mother was making a cake when somebody Knocked at the door.

11. Somebody saw a thief while he was stealing his father's car.

12.He was studying in his bedroom when his mother came in with his sister.

13. Charlie was driving his cat when he saw a cat in the nmiddle of the street.

14.What were you doing when the earthquake started?

15. While she was washing the clothes, it started to rain. She had to use the tumble drier.

16.When my sister came into the room, the dog was eating her homework.

17. She was doing the ironing while her husband was making the bed.

18.Are they working when the light went off?

19.When I met Helen, she was wearing a red dress and was looking pretty. She was the most beautiful girl in the world.

20. The dog was barking in the garden when we arrived at home.

Объяснение:

When

When означает «когда», «пока». Он используется, когда мы хотим сказать о коротком действии, которое прервало другое действие (более длительное) или занимает какое-то время до основного действия.

Кроме того, мы будем использовать when:

+ говоря о периоде в жизни (When I was thirteen — Когда мне было тринадцать лет)

+ если в основном предложении Past Continuous, а в придаточном Past Simple (She was writing a composition when she heard a ring — Она писала композицию, когда услышала звонок)

+ в случае двух коротких действий ( We shook hands when we saw each other — Мы пожали руки, когда увидели друг друга.)

While

While означает «пока», «когда» и используется для двух длительных действий, которые происходят одновременно.

Мы используем while, когда нам важно:

+ подчеркнуть, что действие происходит во время другого действия (He was sleeping while I was writing my exercises — Он спал, пока я (в это самое время) делал свое задание)

+ указать, что что-то произошло во время другого события (While I was cooking dinner, it began to rain — Пока я готовила ужин, пошел дождь)