每个学生学习三门课程以班为单位 能够接收如数的某班每个学生所学习的三门课程成绩 能够根据用户要求按升序或降序输出某班学生各门课程的成绩 能统计并输出系统中共有多少个班-Descr iption of the Project three courses each student to learn mathematical and physical chemistry of students to classes as t