Ответ: The flat of my sister=my sister’s flatthe room of these people = these people’s roomthe son of her mother=her mother’s son the food of those dogs=those dogs’ food the name of this man = this man’s name the hobby of these gentlemen = these getlemen’s hobby the mark of our student = our student’s markthe work of the man = the man’s workthe ball of my child = my child’s ball the friend of Susan = Susan’s friend