设计四个类；学生类（描述学生基本信息）；成绩类：班级类；课程类（描述课程信息：课程编号，科目名称（如高等数学，大学英语等）；学生成绩及课程信息用文件保存，每个类一个文件，程序执行时从文件读入； -Design four classes　student class (describe students basic information)　achievements Class: Class class　curriculum classes (Descr iption Course Information: Course ID, Account Name (eg mathematics, English, etc.)　student achievement and course information saved with the file , one for each class, program execution is read from the file