from the words as in the example
1)the letter of her friend -
2)the nickname of my sister.-
3)the photos of the teachers -
4)the sharpener of his brother.-
5)the felt-tip pens of their sons-
6)disks of the children-
7)the computer of my parents-
Помогите выйти на 4 по английскому

her friend's lettermy sister's nicknamethe teachers' photoshis brother's sharpenertheir sons' felt-tip penschildren's disksmy parents' computer