第12题: [单项选择]传输层主要任务是向用户提供可靠的______。 A. 虚电路服务 B. 点到点服务 C. 分组交换服务 D. 端到端服务 参考答案:D 答案解析:根据分而治之的原则,ISO 将整个通信功能划分为 7 个层次:物理层、数据链路层、网络层、传输 层、会话层、表示层、应用层。其中传输层的主要任务是向用户提供可靠的端到端服务,透明地传送报文。 它向高层
第29题: [单项选择]"Forget football" in Paragraph 1 suggests that football has been ______. A. the fiercest competition at high schools B. thought to have iii impact on students C. competing with commercials on campus D. brought into disrepute by Coke and Pepsi 参考答案:A 答案解析:由the fiercest competition is between Coke and Pepsi over exclusive…可知第一句提到的足球是用来与两大公司之间的竞争做类比。所以表明足球