a. It is Micheal's dictionary.
It is his dictionary.
b. They are Rafi and Cynthia's children.
They are their children.
c. Isn't John's motorcycle in the backyard?
Isn't his motorcycle in the backyard?
See Possessive Adjectives vs Possessive Pronouns Exercise
Possessive Adjectives Subject Exercise 1
Rewrite the sentences using possessive adjectives.