A.Mother and son.
B.Teacher and student.
C.Landlady and tenant.
D.Sister and brother.
A.The boy' s parents.
B.The boy' s summer holiday.
C.The boy' s study.
D.An illness.
A.They are very good parents.
B.They quarrel a lot.
C.They have only one child.
D.They love each other very much.