本系统所完成的是文件的管理，1.输入文件（input） 2.从文件列表中删除一个记录（delete a record from list）， 3.保存文件（save）-The system is completed by the management of documents, 1. Input file (input) 2. From the file list to delete a record (delete a record from list), 3. To save the file (save)