1. boy's toy
2. girl's dress
3. boy's game
4. dog's food
5. mum's plate
6. teacher's bag
7. child's ball
8. father's car
9. granny's flower
Упражнение 21. son's game
2. child's mark
3. dog's life
4. cat's club
5. England's climate
6. Russian history
7. family's problem
8. dad's dinner
9. granny's book
10. mum's dress
Упражнение 31. sons' games
2. kids' marks
3. dogs' lifes
4. cats' clubs
5. towns' climates
6. towns' histories
7. families' problems
upd: если отметьте решение как лучшее ;)