专业英语的复习材料

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