Here are the suitable prepositions for each blank:

1. **in** - The children in our neighborhood are fond of making models and watching cartoons **in** their leisure time.
2. **in** - Some kids don’t like joining the games with classmates but spending time **in** their own.
3. **On** - **On** Sundays, my cousin usually plays football, goes swimming, or plays badminton with his friends.
4. **with** - We should spend time **with** our family because it’s a great way to connect **with** them.
5. **for** - My mom is cooking now, and she always looks **for** different recipes for my family.
6. **On** - **On** special occasions, our family members often make some special dishes for meals.
7. **about** - Mark is so crazy **about** playing computer games that he spends all of his free time at the computer.
8. **in** - My uncle is keen **in** doing karate, and he goes to the karate club every Saturday.