Ответ:

1)1.I caught a cold when I was skating on a frosty day;

2. He wrote those nice poems when he had a holiday;

3. She learnt the language when she lived in England;

4. She heard that song when she was listening to the concert on the radio;

5.I bought this book when I read up for my exams;

6. The boy hurt himself when he was riding a bike;

7.Phillip lost his camera when he was walking around the city;

8.He rang me up when I was having supper.

2)1.The postman brought the letter when I was having breakfast;

2.It started to snow when I went downstairs;

3.The doorbell rang when they were entering the dining room.Удачи