根据下面的文字资料回答 71～75 题 In the following essay，each blank has four choices．Choose the most suitable one from the four choices and write down in the answer sheet．A（ 1 ）is basically an end point of a communication link between two applications.Sockets that extend over a network connect two or more applications running on separate computer sat tached to the network．Asocket（ 2 ）twoaddresses：（ 3 ）．Sockets providea （ 4 ）communication channel between one or more systems.There are stream and datagram sockets separately using TCP and（ 5 ）．

第6题：文中（ 1 ）处正确的答案是（ ）。

A．program

B．UDP

C．socket

D．TCP

CSocket是两个应用之间的联系接口。Socket使网络中不同的计算机之间的应用能够联系在一起。一个Socket有两个地址：端口号和IP地址。Socket提供了在多个系统中全双工通信的方式。TCP在Socket传递的是字符流，而UDP传递的是数据报。