第一组：
1.Tom's and Mary's parents
2.Jack's and John's bags
3.Xiaoming's and Xiaohong's rooms
4.David's and his sister's books
5.Peter's and Jane's bikes
第二组：
1.Tom and Mary's dictionary
2.Jack and John's room
3.Xiaoming and Xiaohong's grandpa
4.David and his sister's kite
5.Peter and Jane's child