一个简化的学生成绩管理系统。假设每位学生必须完成必修课5门，选修课2门。

1.可查看，可增加，可删除学生成绩信息

2.可按学号，教室，总成绩分类排序

3.可按学号查询

4.信息存在磁盘上

-A simplified student achievement management system. Suppose each student must complete five required courses, two elective courses. 1. Can view, increase, information on student achievement could be deleted 2. Can learn numbers, classrooms, a total score of classification to sort 3. According to school for inquiry 4. Information exists on disk