1.He showed me his sister's letter.
2.She took her brother's skates.
3.Give me  our students' copybooks. 
4.Bring the children's things. 
5.Yesterday the children found a bird's nest.
6.This is my friend's Family. My friend's Father is an engineer,  my friend's mother is a teacher.
7.Whose is this bag? This is Tom's bag.
8.All these dictionaries are the students' ones.
9.Have you seen our teacher's book?

1. he showed me a letter from his sisters
2.She took the skates of his brother
3.Give me books our students
4.Bring things children
5.Yesterday, the children found a bird's nest
6.This is my friend's Family the Father of my friend, the engineer, the mother of my friend the teacher.
7.Whose is this bag this bag Volume
8.All these dictionaries, this dictionary students
9.Have you seen our teacher book