Ответ:
1. When I arrived at the cinema, the film had started.

2. She lived in China before she went to Thailand.

3. After they ate too many sweets, they began to feel sick.

4. When we finished dinner, we went out.

5. The grass is yellow because it didn't rain all summer.

6. The lights went off because we didn't pay the electricity bill.

7. My brother ate all of the cake that our mum made.

8. The waiter brought a drink that I ordered.

9. I am very tired because I studied too much.

10. After they had a cup of tea, they had some cake.

11. They sold everything before they moved to Glasgow.

12. They went to a sightseeing tour after the bus arrived.