说明：  StudScore程序描述： 本程序包括：练习文件的保存和读取操作。 学生分数统计和平均计算，生成文件保存成"Stud.txt"文件。
(StudScore procedures Description : The procedures include : the preservation of documents practice and read operations. Statistics and scores of students on average, the file preserved as a "Stud.txt" document.)