Ответ:

1. I didn't tell my teacher that my mum had heloed me with my homework.

2. Paul didn't say that he had taken Albert's watch.

3. The bike was much more expensive than he had thought at first.

4. Dad drove me home after I had fallen into the water.

5. Marion asked me what had happened to me last week.

6. We had eaten two Big Macs before we went home.