抽象出教师、学生和后勤人员的公共特性和方法，使用继承定义教师、学生和后勤人员等新类，每个类都又区别于其他类的特殊属性，构造对应的方法分别计算出教师、学生和后勤人员的人数，计算教师、学生和后勤人员的平均年龄-Abstract teachers, students and support staff of public properties and methods defined using the inheritance of teachers, students and support staf