Here are the appropriate forms for the sentences you provided:

1. Your bag is **easier** (easy) than mine.
2. My mother’s advice is **more useful** (useful) for me.
3. The summer this year is **drier** (dry) as ever.
4. It is the **most difficult** (difficult) rule of all.
5. This pen writes **better** (good) than my previous one.
6. This athlete is **stronger** (strong) than his competitor.
7. This pupil is **cleverer** (clever) in the class.
8. This is **the oldest** (old) castle in Britain.
9. Health is **more important** (important) than money.
10. This path is **narrower** (narrow) than the parallel one.
11. This actor is a **more famous** (famous) actor from Spain.
12. Kevin and Anne are **better** (good) sprinters.
13. Luxurious hotels are **more expensive** (expensive) than those of economic class.
14. My **older** (old) sister is afraid of mice.
15. My Saturn is the **second largest** (large) planet in our solar system.
16. We have **more** (much) homework today than we had yesterday.
17. If you need any **further** (far) information, please contact our assistant.