这是一个学生成绩管理系统，其中“I”表示插入，“L”表示浏览，“Q”表示查询，

“E”表示退出，“D”表示删除，“M”表示修改,"c"表示统计各分数段人数,"p"表示打印-This is a student achievement management system, which " I"　said insert, " L"　that the browser, " Q"　that the inquiry, " E"　that the withdrawal, " D"　to delete that, " M"　that modify, " c" , said the Census and Statistics Score the number of the paragraph, " p"　that the print