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UnitSeven:ComputerCommunicationsUnitSeven/SectionAI.Fillintheblankswiththeinformationgiveninthetext:1.telegraph2.dots;dashes3.media4.point-to-point5.analog6.digital7.text-based8.modemII.TranslatethefollowingtermsorphrasesfromEnglishintoChineseandviceversa:1.microwaveradio微波无线电2.digitaltelevision数字电视3.DSL数字用户线路4.analogtransmission模拟传输5.on-screenpointer屏幕上的指针6.computerterminal计算机终端7.radiotelephone无线电话8.cellulartelephone蜂窝电话，移动电话，手机9.decentralizednetwork分散型网络10.wire-basedinternalnetwork基于导线的内部网络，有线内部网11.光缆fiber-opticcable12.传真机faxmachine13.无线通信wirelesscommunications14.点对点通信point-to-pointcommunications15.调制电脉冲modulatedelectricalimpulse16.通信卫星communication(s)satellite17.电报电键telegraphkey18.传输媒体transmissionmedium(或media)19.无绳电话cordlesstelephone20.金属导体metalconductorIII.Fillineachoftheblankswithoneofthewordsgiveninthefollowinglist,makingchangesifnecessary:Datacommunicationsistheprocessoftransmittingandreceivingdatainanorderlywaysothedatathatarrivesatitsdestinationisanaccurateduplication(复制)ofthedatathatwassent.Whendatatravelsashortdistance,suchaswhenyousenddatafromyourcomputertoyourprinter,itisreferredtoaslocalcommunications.Whendatatravelsalongdistance,thecommunicationisreferredtoastelecommunications;theprefix(前缀)“tele”isderivedfromaGreekwordthatmeans“far”or“faroff.”Thedifferencebetweenashortdistanceandalongdistanceissomewhatarbitrary(武断的).Forexample,ifyourcomputersendsdatatoaprinterinthenextroom,itisregardedaslocalcommunications;ifyouphonethepersoninthenextroom,youaretransmittingdataoveratelecommunicationsdevice.However,thesamebasiccommunicationsconceptsapplytobothlocalcommunicationsandtelecommunications.Basicdatacommunicationsconceptsarethebuildingblocksforunderstandinghowdatatravelsonacommunicationssystem.Theseconceptscomeinhandy(派得上用处)whenyouinstall,configure,orupgradealocalareanetwork.Inaddition,theseconceptshelpyousetupmodems,faxmachines,andcellulardatatransfers.IV.TranslatethefollowingpassagefromEnglishintoChinese:个人计算机使用电信来提供传输链路，用于传送音频、视频、文本、软件和多媒体服务。许多专家认为，这些服务的结合将带来用户对新一代高速、宽带网络的需求。当前，这些音频、视频和文本服务大多通过现有的电话连接使用因特网传送。有些计算机使用综合业务数字网或数字用户线路直接连接到电话网的数字部分，但这要求在用户处有专门的设备。此外，电话及有线电视公司还必须对其线路进行升级，以使其能够进行高速数据传输。在许多地点，有高速数据传输需求的公司和个人现在可选择从电话公司得到数字用户线路服务，从有线电视公司得到光缆调制解调器服务。UnitSeven/SectionBI.Fillintheblankswiththeinformationgiveninthetext:1.controller2.main;CPU3.digital;voice4.parallel;serial或serial;parallelII.TranslatethefollowingtermsorphrasesfromEnglishintoChineseandviceversa:1.bitmap位图，位映象2.parallelport并行端口3.directmemoryaccess(DMA)直接存储器存取4.universalserialbus通用串行总线5.general-purposeregister通用寄存器6.电路板circuitboard7.串行通信serialcommunication8.数码照相机digitalcamera9.存储映射输入/输出memory-mappedI/O10.有线电视cabletelevisionUnitSeven/SectionCI.Fillintheblankswiththeinformationgiveninthetext:1.Transfer2.cells3.label4.integratedII.TranslatethefollowingtermsorphrasesfromEnglishintoChineseandviceversa:1.high-definitionTV高清晰度电视2.framerelay帧中继3.datarate数据（速）率4.metropolitanareanetwork城域网5.机顶盒set-topbox6.多模光纤multi-modefiber7.协议堆栈protocolstack8.虚拟路径标识符VPI(virtualpathidentifier)UnitEight:ComputerNetworksUnitEight/SectionAI.Fillintheblankswiththeinformationgiveninthetext:1.MAN2.open;closed3.bus4.token5.Ethernet6.client/server7.equals;temporary8.networkII.TranslatethefollowingtermsorphrasesfromEnglishintoChineseandviceversa:1.fileserver文件服务器2.carriersense载波检测，载波监听3.protocolsuite协议组，协议集4.peer-to-peermodel对等模型5.bustopologynetwork总线拓扑网络6.inter-machinecooperation机器间合作，计算机间合作7.Ethernetprotocolcollection以太网协议集8.proprietarynetwork专有网络9.utilitypackage实用软件包，公用程序包10.starnetwork星形网络11.局域网localareanetwork(LAN)12.令牌环tokenring13.无线网络wirelessnetwork14.封闭式网络closednetwork15.环形拓扑结构ringtopology16.客户机/服务器模型client/servermodel17.网络应用程序networkapplication18.进程间通信interprocesscommunication19.打印服务器printserver20.广域网wideareanetwork(WAN)III.Fillineachoftheblankswithoneofthewordsgiveninthefollowinglist,makingchangesifnecessary:Computerscancommunicatewithothercomputersthroughaseriesofconnectionsandassociatedhardwarecalledanetwork.Theadvantageofanetworkisthatdatacanbeexchangedrapidly,andsoftwareandhardwareresources,suchashard-diskspaceorprinters,canbeshared.Networksalsoallowremoteuseofacomputerbyauserwhocannotphysicallyaccessthecomputer.Onetypeofnetwork,alocalareanetwork(LAN),consistsofseveralPCsorworkstationsconnectedtoaspecialcomputercalledaserver,oftenwithinthesamebuildingorofficecomplex.Theserverstoresandmanagesprogramsanddata.Aserveroftencontainsallofanetworkedgroup’sdataandenablesLANworkstationsorPCstobesetupwithoutlargestoragecapabilities.Inthisscenario(方案),eachPCmayhave“local”memory(forexample,aharddrive)specifictoitself,butthebulkofstorageresidesontheserver.ThisreducesthecostoftheworkstationorPCbecauselessexpensivecomputerscanbepurchased,anditsimplifiesthemaintenanceofsoftwarebecausethesoftwareresidesonlyontheserverratherthanoneachindividualworkstationorPC.IV.TranslatethefollowingpassagefromEnglishintoChinese:在计算机科学中，网络是指由通信设备连接在一起的一组计算机及其相关设备。网络可采用电缆等永久性连接，或者采用通过电话或其他通信链路而实现的临时性连接。网络可以小到由少数计算机、打印机以及其他设备构成的局域网，也可以由分布在广大地理区域的许多小型与大型计算机组成。计算机网络无论大小，其存在的目的均在于为计算机用户提供以电子方式