Заместо оборота с предлогом 39;of39; образуйте оборот с существительным в притяжательном

the office of Mr. Black - Mr. Blacks office

the children of these women These womens children

the room of my sister My sisters room

the pen of my brother my brothers pen

the book of Mary Marys book

the table of Mr. Smith Mr. Smiths table

the dress of the girl the girls dress

the ball of the boy the boys ball

the doll of the little girl the little girls doll

the horses of the man the mans horses

the hen of Mary Marys hen

the plates of the lady the ladys plates

the baby of the mother the mothers baby