Here are the correct forms of the words for each sentence:

1. It's **important** for children to learn to get on with each other. (importance)
2. He spoke English **naturally** after he lived in England for several months. (nature)
3. The teacher often **emphasized** the importance of studying for the test. (emphasis)
4. She trained very hard to beat her **competitors** in the race. (compete)
5. Her skirt was beautifully **patterned** with flowers and leaves. (pattern)
6. My friend, John, is very **adventurous** and loves to try new things. (adventure)
7. Many countries are still **developing** their economies. (develop)
8. The teacher’s **inspirational** words left a lasting impact on her students. (inspiration)
9. We can help save **natural** resources by collecting used things like paper and cans. (nature)
10. The basketball team **participated** in the match very actively yesterday. (participate)
11. Dreams can be a rich source of **inspiration** for musicians. (inspire)
12. Many designers took **inspiration** from ethnic minorities. (inspire)
13. They are discussing the preservation of **natural** resources. (nature)
14. The baseball team **participated** in the match very actively yesterday. (participate)
15. My uncle **adventurously** signed up for the skydiving course 2 weeks ago. (adventurous)
16. She had some exciting **adventures** in Africa. (adventure)
17. This event attracted more than three thousand **participants**. (participate)
18. It's very **challenging** to find a job in this city. (challenge)
19. Nathan played the game **competitively**, determined to outsmart his opponents and claim victory. (competitive)
20. The teacher explained the topic **informatively**, so everyone understood it. (inform)