1. He is (clever)the cleverest student in my group.
2. She can't stay (long)longer than 30 minutes.
3. It's (good)the best holiday I've had.
4. Well, the place looks (clean)cleaner now.
5. The red shirt is better but it's (expensive)more expensive than the white one.
6. I'll try to finish the job (quick)quickly.
7. Being a firefighter is (dangerous) more dangerous than being a builder.
8. Lan sings (sweet) sweetlier than Hoa.
9. This is (exciting) the most exciting film I've ever seen.
10. He runs (fast) fastest of all.