学生管理系统 能够统计每个学生三门功课成绩并显示； 能按学生号查询其三门学功课成绩并显示； 能浏览全部学生成绩； 能按总成绩由高到低显示学生成绩(Student management system To be able to count the three subjects of each student and show them. It can be found and displayed on the student's number. Can browse al