Here's a list of the correct forms of the words for the exercise:

1. He earns **more** money than his wife (much).
2. He works **more** hours than any workers (many).
3. My father drinks **less** beer than his friends (little).
4. There are **fewer** tourists to come here this year than last year (few).
5. Using a computer is very **interesting**. Ba is very **interested** in computer (interest).
6. You look **happy** today. Why are you so sad? (happy)
7. His **expression** is very difficult to understand. (express).
8. She wants to be a **famous** when she grows up. (compose).
9. There are some **differences** between the city and the countryside. (different).
10. Dong Ho paintings are made with **natural** colours. (nature).
11. I am an **energetic** person. I play a lot of sports and run every day. (energy).
12. They have a wonderful **collection** of old toys at the museum in town. (collect).
13. Be **careful**! I’ve just painted the walls and they’re wet. (care).
14. Last night she **performed** very well. Her **performance** was excellent. (perform).
15. He is a **successful** man. He works **successfully**. (success).

Feel free to ask if you need any more help!