I. 1. b
2. b
3. a
4. c
5. c
6. a
II. 1. bad — worse — the worst
2. dirty — dirtier — the dirtiest
3. weak — weaker — the weakest
4. old — older — the oldest
5. fast — faster — the fastest
6. sad — sad der — the sad dest
7. important — more important — the most important
8. popular — more popular — the most popular