学生成绩管理

主要功能：

（1）能按学期、按班级完成对学生成绩的录入、修改

（2）能按班级统计学生的成绩，求学生的总分及平均分，并能根据学生的平均成绩进行排序

（3）能查询学生成绩，不及格科目及学生名单

（4）能按班级输出学生的成绩单

-The main functions of the management of student achievement: (1) according to semester, according to the class to complete the recording of student achievement, modify (2) according to statistics of the scores of pupils in classes, and scores of students and the average score, and based on the average performance of students sort (3) be able to query student achievement, and students do not pass the list of subjects (4) classes according to the output of students report card