Ex7:
1. I prefer walking to taking a bus
2. she prefers listening to music to watching TV
3. We prefer playing tennis to skipping
4. They prefer collecting stamps to playing sports
5. He prefers helping old people to cleaning the house
EX8:
1. paint
2. bought
3. is helping
4. was- missed
5. taught
6. watches
7. makes
8. will have
9. visited
10. won't have
11. went
12. learned
13. did - die
14. is coming
15. is going to