单选题 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 socket 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 (31) computers attached to the net-work. A socket (32) two addresses: (33) . Sockets provide a (34) communication channel between one or more systems. There are (35) sockets separately using TCP and UDP.

单选题 A. unique B. separate C. same D. dependent
【正确答案】 B
【答案解析】
单选题 A. is made of B. composed of
C. is composed of D. is consisted of
【正确答案】 C
【答案解析】
单选题 A. Email address and IP address B. MAC address and port address
C. MAC address and IP address D. port number and IP address
【正确答案】 D
【答案解析】
单选题 A. full-duplex B. half-duplex C. simplex D. complex
【正确答案】 A
【答案解析】
单选题 A. message and packet B. packet and frame
C. stream and datagram D. flow and block
【正确答案】 C
【答案解析】[解析] socket套接字基本上是两个不同主机的应用程序进程之间的通信的端点。在网络上扩展的socket连接两个或者多个应用程序,这些应用运行在网路上的各个主机上。socket需要两个地址:IP地址和端口号。Socket在一个或者多个系统之间提供了全双工(full-duplex)的通信方式。有流式套接字和数据报式套接字,它们分别使用TCP和UDP。