1. The dog's ball
2. The children's songs
3. My friend's room
4. The workers' new club
5. My parents' car
6. My sister's flat is large
7. My brother's children are at home
8. These students' work is interesting
9. This girl's name is Jane
10. My son's computer is modern
притяжательный падеж - к владельцу добавляется 's если на конце слова нет "s" и ' если на конце слова есть "s"