说明：  提供了一个用C#语言实现的txt文件操作类，实现了写入txt、读取txt、读取指定行、删除指定行、查询txt指定内容，按照给定条件查询、删除txt文件内容等功能。调用方便，操作简单，附有使用说明。
(Provides a C# language using the txt file manipulation class realized write txt, read txt, reads the specified line, delete the specified row, query txt specified content, in accordance with the conditions given query, delete the txt file content and so on. Call convenient, easy to operate. )