通信英语 I单项选择 抽样频率 a. sampling rate b. repetition rate c. sampling frequency 答案：c 数字通信 a. digital communication b. digital transmission c. transmission path 答案：a 帧格式 a. synchronization word b. frame format c. reverse operation 答案：b 噪声功率 a. noisy environment b. signal levels c. noise power 答案：c 含噪声的环境 a. signal levels b. noisy environment c. noise power 答案：b 模拟信号 a. speech channel b. analog signal c. amplitude value 答案：b 脉冲流 a. stream of pulses b. receiving terminal c. terrestrial system 答案：a 传输路由 a. transmission path b. transmission quality c. binary transmission 答案：a 互联网 a. network resource b. Internet c. interconnected systems 答案：b 命令 a. copy b. host c. command 答案：c 拷贝 a. address b. mouse c. copy 答案：c 搜索工具 a. user interface b. searching tools c. electronic mail 答案：b 存取 a. access b. protocol c. copy 答案：a 网络资源 textual messages b. remote terminals c. network resources 答案：c 文本信息 a. information services b. hypertext protocol c. textual messages 答案：c 频谱 a. bandwidth b. spread spectrum c. frequency band 答案：b 移动手机 a. mobile subscriber b. mobile unit c. service performance 答案：b 频带 a. frequency spectrum b. frequency band c. spread spectrum 答案：b 蜂窝交换机 a. cellular switch b. cellular site c. mobile unit 答案：a 单边带 a. single-sideband b. bandwidth c. service area 答案：a 服务区 a. service area b. service performance c. service capability 答案：a 移动用户 a. mobile unit b. mobile subscriber c. mobile transceiver 答案：b 微处理器 a. subsystems b. utilization c. microprocessor 答案：c 无线机架 a. radio cabinet b. antenna c. mobile unit 答案：a 电路交换 a. packet switching b. circuit switching c. message switching 答案：b 分组交换 a. packet switching b. circuit switching c. message switching 答案：a 报文交换 a. packet switching b. circuit switching c. message switching 答案：c 专用电路 a. dedicated circuit b. error control c. return signal 答案：a 突发性 a. bursty b. random c. header 答案：a 传输时延 a. destination address b. transmission delay c. return signal 答案：b 中间交换设备 a. given maximum b. intermediate switching equipment c. store-and-forward manner 答案：b 子网 a. header b. subnet c. busty 答案：b 33. 公众电信网 public telecommunication network b. intermediate switching node c. circuit- switched network 答案：a 34.半双工的 a. full-duplex b. half-duplex c. external call 答案：b 端局 a. toll center b. end office c. tandem switch 答案：b 外部呼叫 a. external call b. data traffic c. toll center 答案：a 链路 a. trunk b. link c. route 答案：b 交换节点 a. intermediate switching node b. voice-frequency circuit c. switching node 答案：c 音频电路 a. telephone subscriber b. voice-frequency circuit c. two wire connection 答案：b 拓扑 a. internodes b. topology c. route 答案：b 二线连接 a. data traffic b. end office c. two wire connection 答案：c 数据流量 a. data traffic b. tandem switch c. toll center 答案：a 全球通信 a. interface equipment b. global communication c. communication carriers 答案：b 脉码调制 a. pulse code modulation b. voice encoding c. open network 答案：a 接口设备 a. switching equipment b. transmission medium c. interface equipment 答案：c 综合业务数字网 end-to-end digital connectivity b. international organization for standardization c. integrated services digital network 答案：c 通信载体 a. communication carriers b. transmission medium c. interface equipment 答案：a 系统结构 a. infrastructure c. flexibility d. basic access 答案：a 49.蜂窝式移动电话 a. cellular switch b. cellular mobile telephone c. cellular site 答案：b 50.数据传输 a. data transmission b. transmission error c. error flag 答案：a 51.传号电平 a. space level b. logical level c. mark level 答案： c 52.接收机的定时 a. intersymbol space b. serial interface c. receiver timing 答案：c 53.明显的缺点 a. transmission error b. obvious disadvantage c. error flag 答案：b 54. 起始位 a. start bit b. stop bit c. parity bit 答案：a 空号电平 a. mark level b. space level c. the idle state 答案：b 控制比特 a. binary data b. local clock c. control bit 答案：c 串行接口 a. data stream b. CRT terminal c. serial interface 答案：c 发送器和接收器 a. transmitter and receiver b. receiver timing c. duration of T seconds 答案：a 二进制数据 a. binary data b. data stream c. data transmission 答案：a 高速电子开关 a. the voice channel b. the repetition rate c. a high-speed switch 答案：c II.根据所给英文选择合适的答案 digital communication a.全球通信 b. 公共通信载体 c.数字通信 答案：c voice encoding techniques a.语音编码技术 b. 脉冲 c. 脉冲编码调制 答案：a basic access signaling rate a.大量的接口设备 b. 基本接入信令速率 c. 统一的接入 答案：b the International Organization for Standardization a.综合业务数字网 b. ISDN的标准和系统结构 c. 国际标准化组织 答案：c end-to-end digital connectivity a. 基本接入信令速率 b.端对端的数字连接 c. 语音编码技术 答案：b progressive application of digital technology 由于传输媒体导致的质量下降 4KHz 话路中所固有的带宽限制 数字技术的逐步应用 答案：c enhanced quality a.高质量 b. 带宽的限制 c.统一的接入 答案：a the branches between nodes a.节点间的支路 b. 中间交换节点 c. 全双工的连接 答案： a tree topology a. 双绞线 b. 结构部件 c. 树状拓扑 答案：c backbone hierarchical network a. 国家网络 b. 被分离开的子网 c. 主干体系网络 答案：c the subscriber that transmit digital signal a. 发送数字信号的用户 b. 一小部分用户 c. 相邻的端局 答案：a multiple voice-frequency circuits a. 高效中继线 b. 多音频电路 c. 同步时分复用 答案：b the function of concentrating traffic a.集中话务量的功能 b. 路由选择的基本次序 c. 发送数字信号的用户 答案：a full duplex a. 全双工的连接 b. 全连通性 c. 全双工的 答案：c transmission facilities a. 传输设备 b. 交换区 c. 高效中继线 答案：a switching technique a.交换技术 b. 电路交换 c. 分组交换 答案：a message switching a.交换技术 b. 报文交换 c. 分组交换 答案：b communication parties a.传输单元 b. 通信各方 c. 返回信号 答案：b the special signaling message a. 存储转发传输技术 b. 带宽的动态分配 c. 特定的信令信息 答案：c low channel utilization a. 低的电路利用率 b. 报文整个的传输时延 c. 传输单元 答案：a total path of connected lines a. 连线的整个通路 b. 源到目的地的一对 c. 带宽的动态分配 答案：a radio cabinet a. 无线通信行业 b. 无线机架 c. 多径衰耗 答案：b telephone company zone offices a.移动收发信机 b. 电话公司地方局 c. 中央协调单元 答案：b available radio frequency spectrum a. 所分配的频带 b. 调频广播业务 c. 可用的无线电频谱 答案：c central coordinating element a. 中央协调单元 b. 试验性的蜂窝系统 c. 有限的服务能力 答案：a severe spectrum limitations a.严厉的频谱限制 b. 有限的服务能力 c. 有限的指定频带 答案：a developmental cellular system a. 频谱利用率 b. 试验性的蜂窝系统 c. 传统移动电路的运行限制 答案：b propagation path loss a. 调频广播业务 b. 传输路径衰耗 c. 无线机架 答案：b backbone system a.主干系统 b. 电子会议 c. 远程终端 答案：a live conversation a.最大的信息库 b. 文本信息 c. 实时的对话 答案：c textual messages a.搜索工具 b. 万维网 c. 文本信息 答案：c the networked hypertext protocol a.联网的超文本协议 b. 网络设备资源 c. 全国范围的网络 答案：a the Unix operating system a. 主干系统 b. 万维网 c. Unix 操作系统 答案：c the vast majority of the computers on the net a.在网上的绝大多数计算机 b. 分布在全世界的计算机的巨大网络 c. 全国范围的网络 答案：a remote terminal a. 电子会议 b. 远程终端 c. 文本信息 答案：b the largest repository of information a. 最大的信息库 b. 实时的对话 c. 方便的搜索工具 答案：a the time division multiplexer a. 时分多路复用 b. 高速的电子开关 c. 时分多路复用器 答案：c A high-speed electronic switch a. 高速的电子开关 b. 被传信号的波形 c. 时分多路复用 答案：a time Division Multiplexing a. 时分多路复用 b. 时分多路复用器 c. 地面系统 答案：a the presence or absence of the pulse a. 一串幅值 b. 每样值8 位码 c. 脉冲的“有”或“无” 答案：c the unique or absence of the pulse a. 脉冲的“有”或“无” b. 被称为同步字的独特的码序列 c. 将抽样的幅值转换成一串脉冲的单元 答案：b A sequence relating to channel1, 2 and so on 涉及到第一路、第二路及其他各路的序列 一条特定消息中的全部信号 理论上的最小采样频率 答案：a the schemes for performing these three functions a. 电话质量的话路 b. 由卫星上收到的信号 c. 实现这三项功能的方案 答案：c a series of amplitude values a.一串幅值 b. 被传信号的波形 c. 每样值8位码 答案：a A speech channel of telephone quality a. 实现这三项功能的方案 b. 将抽样的幅值转换成一串脉冲的单元 c. 电话质量的话路 答案：c A sequence of 8-binary digits a. 每样值8位码 b. 一个8位二进制序列 c. 一串幅值 答案：b A minimum theoretical sampling frequency a. 理论上的最小采样频率 b. 抽样量化和编码 c. 将抽样的幅值转换成一组脉冲的单元 答案：a the sparking of a car ignition system a. 高速电子开关 b. 理论上的最小采样频率 c. 汽车点火系统的打火 答案：c the stream of the pulses with a repetition rate of 64KHz a. 真实信号与噪声信号的关系 b. 由传输路由引入的衰减 c. 重复率为64KHz的脉冲流 答案:c the relationship of the true signal to the noise signal a. 真实信号与噪声信号的关系 b. 脉冲的有和无 c. 被称为同步字的独特的码序列 答案：a terrestrial system a. 高速电子开关 b. 地面系统 c. 时分多路复用 答案：b asynchronous serial data transmission a. 数据链路面向字符的特征 b. 异步串行数据传输 c. 异步串行接口 答案：b isolated subnetworks a. 被分离的子网 b. 高效中继线 c. 交换区 答案：a two subscribers attached to different end offices a. 在站和网络之间的接口 b. 路由选择的基本次序 c. 连到不同端局的两个用户 答案：c synchronous TDM a. 同步时分复用 b. 多条音频电路 c. 节点间的之路 答案：a the clocks at the transmitter and receiver a. 符号间空格持续时间的三倍 b. 在字符后所收到的奇偶校验位 c. 发送器和接收器时钟 答案：c the transmitted data a. 电传机时代 b. 一个字符的点和划 c. 所发送的数据 答案：c the falling edge of the start bit a. 起始位的下降沿 b. 停止位的下降沿 c. 电传机时代 答案：a the group of bits called characters a. 数据链路面向字符的特征 b. 在字符后所收到的奇偶校验位 c. 被称为字符的比特组 答案：c A clock generated locally by the receiver a. 最为流行的串行接口 b. 由接收机本地产生的时钟 c. 发送器和接收器的时钟 答案：b III.选择合适的答案 1.Furthermore, we shall prove that a minimum theoretical sampling frequency of order 6.8KHz is required ( ) a voice channel ( ) the range 300 Hz to 3.4KHz. a. convey , occupy b. to convey, occupying c. conveying , occupied d. convey, to occupy 答案：b 2. For example, the signal ( ) from a satellite, ( ) in far outer space, is very weak. ａ. received, located b. receive, locate c. receiving, locating d. to receive, to located 答案：a 3. If we consider binary transmission, the complete information about a particular message will always (　) by simply ( ) the presence or absence of the pulse. ａ.obtain, detect b. be obtained, detecting c. obtained, detected d. obtaining, detected 答案：ｂ 4. There is a inherent advantage for ( ) noisy environments by ( ) digital transmission. ａ．overcoming, choose b. overcome, choosing c. overcome, choose d. overcoming , choosing 答案：d 5. Each voice channel has a separate coder, the unit ( ) converts sampled amplitude values to a set of pulse; and decoder, the unit ( ) performs the reverse operation. ａ．who, who b. when, when c. where, where d. that , that 答案：d 6. The problem is easily overcome by ( ) a frame format, where at the start of each frame a unique sequence of pulses is placed ( ) the start of the frame. specify, identify b. specifying, so as to identify c. specified, identified d. specify, identifying 答案：b 7. It was ( ) in 1969, when the U.S. Department of Defense established a nationwide network ( ) a handful of universities and contractors. a. start, connect b. started, to connect c. to start, connected d. to start, to connect 答案：b 8. If somebody else had something interesting ( ) on their computer, it was a simple matter ( ) a copy. stored, to obtain b. to store, obtained c. storing, obtaining d. store, obtain 答案：a 9. The Internet is a huge ( ) systems, but it users just a handful of method ( ) data around. interconnect, move b. interconnected, to move c. to interconnect, moved d. interconnecting, moving 答案：b 10. The most commonly ( ) is electronic mail (E-mail) , or simply as mail, Mail permits network users ( ) textual messages to each other. use, send b. to use, sent c. used, to send d. using , sending 答案：c 11. Today thousands of network s and millions of computers ( ) the Internet. are connected to b. connected to c. to connect d. connecting to 答案：a 12. The simplest way ( ) a file on another host is to copy it across the network to your local host, FTP can do this. access b. to access c. accessed d. success 答案：b 13.One of many reasons for ( ) a cellular mobile telephone system and ( ) it in many cities is the conventional mobile telephone system. develop, deploy b. to develop, to deploy c. developing, deploying d. developed, deployed 答案：c 14. The ideal mobile telephone system would operate within a ( ) signed frequency band and would serve an almost ( ) number of users in ( ) areas. limited, unlimited, unlimited limitation, limitation, limitation limit, limit, limit d. limiting, limiting, limiting 答案：a 15. LSI technology and mass production contribute to reduced cost ( ) in the future an average-income family should be able ( ) a mobile telephone unit. Which, affording b. that, afforded c. when, afford d. so that, to afford 答案：D 16. Microprocessors and minicomputers are now ( ) for controlling many complicated features and functions with less power and size ( ) was previously possible. a. used, than b. use, this c. using, they d. usage, it 答案：a 17. On Jan.4,1979, the FCC ( ) Illinois Bell Telephone Co. ( ) a developmental cellular system in the Chicago area and make a limited offering of its cellular service to the public. a. authorize, conduct b. authorizing, conducting c. authorized, to conduct d. to authorize, conducted 答案：c 18. Why 800 MHz? The FCC’s decision ( ) 800 MHz was ( ) because of severe spectrum limitations at lower frequency band. to choose, made b. choose, to make c. choice, make d. choice, making 答案：a 19. The switch, ( ) circuit switches, have no capability of ( ) user’s data on their way to the destination. a. calling, stored b. called, storing c. to call, to store d. be called, be stored 答案：b 20. The circuit is set up by a special signaling message ( ) finds its way through the network, ( ) channels in the path as it proceeds. a. that, seizing b. where, seizing c. who, seized d. one, be seized 答案：a 21. –The switching element is a computer ( ) a message processor, with processing and storage capabilities. Message travels independently and asynchronously, ( ) their own way from source to destination. a. to call , find b. calling, found c. referred to as, finding d. be called, sending 答案：c 22. A variation of message switching is packet switching. Here the message is broken up into several pieces of a ( ) maximum length, ( ) packets. a. given, called b. give, call c. giving, calling d. to give, to call 答案：a 23. The telephone contains a transmitter and receiver for ( ) back and forth ( ) analog voice and analog electrical signals. a. convert, in b. converting, between c. conversion, to d. converted, into 答案：b 24. Each subscriber connects ( ) local loop to a switching center, ( ) as an end office. a. to, calling b. with, known c. the , know d. via, known 答案：d 25. The trunks are designed ( ) multiple voice-frequency circuits ( ) either FDM or synchronous TDM. a. carry, use b. carried, used c. to carry, to use d. to carry, using 答案：d 26. Although originally to service analog telephone subscribers, the telephone network handles substantial data traffic ( ) modem, and gradually being converted to a digital network. a. implemented, via b. implementing, in c. to implement, within d. design, on 答案：a 27. Designers have found it convenient ( ) these nodes into a hierarchy or tree topology, ( ) five classes of switching centers or nodes. a. organization, consist b. organize, consisting c. to organize, consisting of d. organizing , to consist 答案：c 28. ISDN’s enormous importance is only gradually being ( ) . Years of work have been ( ) by the CCITT and the ISO. a. understand, carry b. understanded, carried c. to be understood, to carry d. understood, carried out 答案：d 29. The term ISDN was first defined within the CCITT in 1972. It referred to a network ( ) end-to-end digital connectivity ( ) a range of services. a. providing, for b. provision, to c. provided, with d. provide, into 答案：a 30. Similarly, the introduction of voice encoding techniques ( ) pulse code modulation contributed ( ) the ISDN’s concept evolution. a. usage, on b. using, to c. use, with d. used, so as to 答案：b 31. The enhanced quality is achieved when a signal is digitally encoded ( ) degradation ( ) the transmission medium. a. overcome, to b. overcame, with c. overcoming, over d. to overcome, due to 答案：d 32. As regards economy, early studies suggested that digital services ( ) significant advantages since a substantial quantity of interface equipment in the telephone exchange could ( ). a. offered, be eliminated b. offer, eliminate c. offers, is eliminated d. to offer, to eliminate 答案：d 33. As regards economy, early studies suggested that digital services ( ) significant advantages since a substantial quantity of interface equipment in the telephone exchange could ( ). a. offered, be eliminated b. offer, eliminate c. offers, is eliminated d. to offer, to eliminate 答案：a 34. If we consider binary transmission, the complete information about a particular message will always ( ) by simply ( ) the presence or absence of the pulse. a. obtain, detect b. be obtained, detecting c. obtained, detected d. obtaining, detected 答案：b 35. An asynchronous serial data link is said ( ) character oriented, as information is transmitted in the form of group of bits ( )characters. a. be, calling b. to being, to call c. been, call d. to be, called 答案：d 36. It was ( ) in 1969, when the U.S Department of Defense established a nationwide network ( ) a handful of universities and contractors. a. start, connect b. started, to connect c. to start, connected d. to start, to define 答案：b 37. Thus was born a new, but perpetually ( ) paging services ( ) at a one-way selective signaling system without speech. a. developing, consisting b. organize, consist of c. develop, define d. to develop, to define 答案：a 38. Designers have found it convenient ( ) these nodes into a hierarchy or tree topology, ( ) five classes of switching centers. a. organizing, consisting b. organize, consist of c. to organize, consisting of d. to organize, to consist of 答案：c 根据课文内容选择正确答案 1.The integrated services digital network is the road map to the future for ( ). all forms of data communications all forms of digital communications all voice conversations all personal communications 答案：B 2. The digital service offered the public carriers three very appealing characteristics: ( ) , economy, and flexibility. A. social ability B. great capacity C. high speed D. enhanced quality 答案：D 3. As regards economy, early studies suggested that digital services offered significant advantages since the substantial quantity of interface equipment in the telephone exchange ( ). A. could be eliminated B. could be used C. could be decreased D. could be widely used 答案：A 4. Today two 64 kbit/s, or 2B-channels coupled with a basic access signaling rate of 16 kbit/s, the D-channel, constitute ( ). the information superhighway the local area network the essential ISDN transmission rate the synchronous digital hierarchy 答案：C 5. Currently PSTN offers universal voice access to almost 750 million telephone around the world. ISDN is the network which will provide a similar universal access for ( ). voice service as well not only voice but data, video, text, and other services as well any analog information including voice high speed data service 答案：B 6. The public telecommunications network can be described ( ). using twisted pair of wires using many thousands of subscribers using four generic architectural components using switching nodes 答案：C 7. The local loop is a pair of wires, generally twisted pair, that ( ). connects a subscriber to one of the nodes in the network connects trunk in the network attaches to the toll center attaches to the primary center 答案：A 8. If the two subscribers are under the aegis of different regional centers, the circuit ( ). will involve a digital data system will involve a trunk between regional centers will involve a PBX facility will involve many end offices 答案：B 9. Each subscriber c9onnects via local loop to a switching center, known as ( ). A. a regional center B. a tandem switch C. an end office D. a telephone network 答案：C 10. There are over 19,000 end offices in the United States, so it is clearly impractical ( ). for each end office to have a direct link to each other end office for the US to build so many switching centers for each end office to provide video service for each end office to support many thousands of subscribers 答案：A 11. With the introduction of digital data system, some subscribers that ( ) have been incorporated into the network. can provide video service transmit broadband program contain a transmitter and receiver transmit digital signals 答案：D 12. ( ) , a total path of connected lines is set up from the origin to the destination at the time the call is made, and the path remains allocated to the source-destination pair until it is released by the communication parties. A. In message switching B. In packet switching C. In circuit switching D. In digital switching 答案：C 13. In message switching, the transmission unit is a well defined block of data called a message. In addition to the text to be transmitted, a message comprises ( ). A. a start and end of data B. a header and checksum C. a start and a stop bit D. a transmitter and receiver 答案：B 14. A variation of message switching is packet switching. Here the message is broken up into several pieces of a given maximum length, ( ). A. called information B. called texts C. called packets D. called messages 答案：C 15. The header of a message contains information regarding ( ); the checksum is used for error control purposes. A. the text to be transmitted B. the source and destination addresses C. the voice channels D. many packets between two computers 答案：B 16. With circuit switching, there is always an initial connection cost incurred in setting up the circuit. It is cost-effective only in those situations where once the circuit is set up ( ). the voice conversation begins there is no any intervention on the part of the subnet there is a message to be transmitted there is a guaranteed steady flow of information transfer 答案：D 17. A major problem facing the radio communication industry is the limitation of ( ). the LSI technology the poor service performance the available radio frequency spectrum the size of the mobile transceivers 答案：C 18. Large-Scale Integrated circuit technology reduced ( ) so that they easily fit into the standard automobile. the costs of the transceivers the size of mobile transceivers the number of the channels the frequency band of the transceiver 答案：B 19. A basic cellular system consists of three parts: a mobile unit, ( ). a cell site, and a mobile telephone switching office a cellular processor and a cellular switch a control unit and a power plant an antenna and a data terminal 答案：A 20. Each mobile unit can only use one channel at a time for its communication link, ( ). the channel is fixed when the call is made but the channel is not fixed and the channel is a high-speed data link and many mobile units use the same channel 答案：B 21. The cellular switch, which can be either analog or digital, switches calls ( ). to connect mobile subscribers to the nationwide telephone network to connect fixed telephone subscribers to one another to link together many fixed telephone users using the microwave radio links 答案：A 22. People on the ARPNET quickly discovered that they could ( ) . communicate to one another by telephone exchange messages and conduct electronic “conferences” with distant conduct data communications get all kinds of information services, such as science, education 答案：B 23. Today thousands of network and millions of computers are connected to the Internet. It is growing so quickly ( ) how many users “On the Net”. A. that anybody knows B. that you can tell us C. that anyone can say exactly D. that nobody can say exactly 答案：D 24. The Internet is an international collection of computer networks that ( ), connected together through backbone systems. all understand a standard system of addresses and commands all have the bridges and gateways all use the same addresses and the servers all understand importance of communications 答案：A 25. The Internet is the largest repository of information which can provide very very large network resources. The network resources can be divided into ( ). communication resources and computer resources servers resources and bridges resources facilities resources and information resources hardware resources and software resources 答案：C 26. As more and more systems join the Internet, and as more and more forms of information can be converted to digital form , ( ). the amount of stuff available to Internet users continues to grow the Internet becomes very busy the number of Internet users becomes very large the information in Internet is shared by more people. 答案：A 27. Before you can use the Internet, you must ( ). understand the regulations of the Internet choose a way to move data between the Internet and your PC install a server study the concept of the communications 答案：B 28. ( ) is a networked hypertext protocol and user interface. A. Asynchronous serial interface B. E-mail C. Internet D. World wide web 答案：D 29. If the signal is very large compared to the noise level, then ( ). the signal-to-noise ratio is poor a perfect message can take place it’s a terrestrial system the noise power is very strong 答案：B 30. If we consider binary transmission, the complete information about a particular message will always be obtained ( ). by detecting the shape of the transmitted signal by detecting the level of the transmitted signal by calculating the parameters of the transmitted signal by detecting the presence or absence of the pulse 答案：D 31. At the receive terminal ( ) to separate the 8-digit sequences into the appropriate channels. A. PCM is used B. a demultiplexer is needed C. the frame code is arranged D. the coder is required 答案：B 32. It is ( ) which is of the most interest to the communication engineer. the method for overcoming noisy environments the relationship of the true signal to the noise signal the binary transmission the quality of the transmission 答案：B 33. The codec is arranged ( ), and code this value into the 8-digit sequence. to do these operations to perform these functions to transmit the voice channels to sample the amplitude value 答案：D 34. Digital transmission ( ) for overcoming noisy environments. provides a program provides a powerful method provides the thermal low-level noise provides the signal-to-noise ratio 答案：B 35. The signal ( ) is very weak. within terrestrial system within communication equipment received from a satellite in a particular message 答案：C 36. The shape of the transmitted signal are most easily affected by the noise and attenuation ( ). introduced by the transmission path introduced by the satellite introduced by the equipment introduced by the codec 答案：A 37. The demultiplexer knows which group of 8-digits relates to channel ( ). by choosing digital transmission by identifying the synchronization word by word interleaving by binary transmission 答案：B