Answer:
1.When I phoned my friends they played monopoly.
2.Yesterday at six I prepared dinner. 3.The kids played in the garden when it suddenly began to rain. 4. I practiced the guitar when he came home. 5. We already cycled all day.
[unsure of number 5.] 6. While Alan worked in his room, his friends swam in the pool. 7. I tried to tell them the truth but they didn't listen. 8. Most of the time we sat in the park. 9. I listened to the radio while my sister watched TV. 10. When I arrived, they played cards.