说明：  用C#实现基于TCP协议的网络通讯 。TCP协议是一个基本的网络协议，基本上所有的网络服务都是基于TCP协议的，如HTTP,FTP等等，所以要了解网络编程就必须了解基于TCP协议的编程。
(To use C# to achieve network communication based on TCP protocol. TCP protocol is a basic network protocols, essentially all of the network services are based on TCP protocol, such as HTTP, FTP, etc. Therefore, to understand the network programming is necessary to understand the programming based on TCP protocol.)