第八单元
选择题
1.The earliest method of delivering telecommunications is the Telegraph
2.With Digital technology ,the electrical impulses only need to correspond to two
digits instead of the full range of qualities that compose the original message.
3.A(n) Modem is a device that converts between analog and digital signals,making
it possible for a computer to transmit information over a standard telephone line.
4.D ata communications is the process of transmitting and receiving data
in an orderly way so the data that arrives at its destination is an accurate duplication of the data that was sent.
5.Basic data communications concepts are the building blocks for understanding
how data travels on a communications system.
第九单元
选择题
1.These high-speed data services are usually referred to as broadband connections.It
is anticipated that they will provide the necessary links between LANs that make what is called the information superhighway a reality
2. A public key system allows users to scramble and unscramble their messages
easily without a third party intruding.
3.The devices on a LAN are known as nodes, and the nodes are connected by
cabling through which messages are transmitted. Nodes on a LAN can be wired together in any of three basic topologies, known as bus, ring, and star.
阅读理解
A local area network (LAN) is a group of computers and other devices dispersed (分散) over a relatively limited area and connected by a communications link that enables any device to interact with any other on the network. LANs commonly include microcomputers and shared (often expensive) resources such as laser printers and large hard disks.Most (modern) LANs can support a wide variety of computers and other devices. Each device must use the proper physical and data-link protocols for the particular LAN, and all devices that want to communicate with each other on the LAN must use the same upper-level communications protocol. Although single LANs are geographically limited(to a department or an office building, for example), separate LANs can be connected to form larger networks. Similar LANs are linked by bridges, which act as transfer points between networks;dissimilar LANs are linked by gateways, which both transfer data and convert it according to the protocols used by the receiving network.
The devices on a LAN are known as nodes, and the nodes are connected by cabling through which messages are transmitted. Nodes on a LAN can be wired together in any of three basic topologies, known as bus, ring, and star.
对应翻译：
局部区域网路（ LAN ），是一组计算机和其他设备的分散（分散）的一个相对有限的地区，并连接由通信联系，让任何装置，以进行互动与任何其他对网络。

局域网常见的包括微型计算机和共享（通常是昂贵的）的资源，例如激光打印机和大硬盘。

大多数（现代）的局域网，可支持多种计算机及其他设备。

每一个设备必须使
用适当的物理和数据链路协议，为特定网络，以及所有的设备要相互沟通在局域网上必须使用同一高层通信协议。

虽然单个局域网相距有限公司（以一个部门或办公楼，举例来说），分别局域网可以连通，形成较大的网络。

类似局域网的连接桥梁，那些充当传递点之间的网络;异种局域网连接，由网关，这两个公司的数据传输和转换，它根据该议定书所使用的接收网络。

该装置对局域网被称为节点，节点是可以互相布线通过这些讯息传送。

节点局域网，可有线一起在任何3个基本拓扑，称为巴士，戒指，和明星
第十单元
选择
1.URLs are Internet addresses used by Web browsers to locate.
网址使用网络浏览器来定位的互联网地址。

第11单元
选择
1.Human societies throughout history have had “information specialists”(form
traditional healers to newspaper editors);
rmation-processing has become increasingly visible and important in economic ,
social, and political life.One familiar piece of evidence is the statistical growth of occupations specializing in information activities
3.The term “Information-processing”covers the generation,storage, transmission,
manipulation,and display of information,including numerical,textual,audio,and video data
rmation-processing involves the generation,storage,transmission,manipulation,and。