Here are the answers for the blanks in the exercise:

1. You have to keep your **distance** from that snake. (DISTANT)
2. They are **warmly** greeted by the native. (WARM)
3. The **performance** by the little girl was a great hit. (PERFORM)
4. Some young people today have a very strange **appearance**. (APPEAR)
5. You don't have to do that work. In other words, it's **unnecessary** for you. (NECESSITY)
6. Although she is rich, she lives **unhappily**. (UNHAPPY)
7. They went to see most of the **interesting** places. (INTEREST)
8. Air **pollution** makes us unhealthy. (POLLUTE)
9. They have made careful **preparations** for the demonstration. (PREPARE)
10. We all looked **healthy** after the summer holiday. (HEALTH)