4-A
5-B
6-B

b
a
b
b
a

4 => a
5 => b
6 => b
7 => a
8 => a

4a 5a 6b 7b 8a           

This is Peter’s book.
 Let’s go to the Smiths’.
The children’s room is upstairs.
John’s sister is twelve years old.
Susan and Steve’s school is old.
Men’s shoes are on the second floor.
My parents’ car was not expensive.
Charles’s CD player is new.
This is the boy’s bike.
These are the boys’ pencils.