Complete the exercise using the correct apostrophe.
 1-This is..........book. (Peter)
 2-The..............room is upstairs. (children)
 3-.......sister is twelve years old. (John)
 4-.......and........school is old. (Susan-Steve)
 5-...........shoes are on the second floor. (men)
 6-My........car was not expensive. (parents)
 7-...........CD and player is new. (Charles)
 8-This is the..........bike. (boy)
 9-These are the........pencils. (boys)