说明：  一、计算机网络概念：计算机网络就是将分布在不同地理位置，具有独立功能的多个计算机系统，通过通信介质按一定的结构结合在一起，再配上相应的网络软件以实现资源共享和数据交换的综合系统。 中心计算机 远端计算机 远端计算机 远端计算机
(First, the concept of computer networks: computer networks that will be distributed in different geographic locations, having individual functions, multiple computer systems, through the communication media, combined with a certain structure, matched with the appropriate network software to share resources and data exchange integrated system. Center for Computer Remote Computer Remote Computer Remote Computer)