1. I was watching TV when the phone rang.

2. She was cooking dinner when her friend arrived.

3. They were walking home when it started to rain.

4. He was reading a book when his sister called him.

5. We were playing football when the sun went down.

I hope that everything is correct:)

Ответ:

1)watching

rang

2)cooking

arrived

3)walked

started

4)reading

called

5)playing

went