计算机英语第10章.ppt

第10章Network,本章要点WhatisaNetwork?WordsandExpressionsHowToDo:ASearchToolHowToWork：SecuritysuitesGrammarFocus：倒装句及句子种类TextinChinese：网络ReadingSelection:AHome(Page)ofYourOwn科技英语翻译方法与技巧（）PracticalWriting：标点符号,WhatisaNetwork?,Throughouttheworld,yourmicrocomputercanconnecttoothermicrocomputers,totheInternet,andtolargercomputersthroughtheelectroniccommunicationsystems.Theelectroniccommunicationsystemstransmitinformationovercommunicationlinesofcableandairfromonelocationtoanother.Suchelectroniccommunicationlinesareknownasnetworks(Figure10-1).Anetworkcanbearrangedinseveraldifferentwaystomeetdifferentusersneeds.Thenetworkarrangementiscalledthenetworkstopology.Thefourprincipaltopologiesarestar,bus,ring,andhierarchical.Inastarnetwork,anumberofsmallcomputersorperipheraldevicesarelinkedtoacentralunitmaybeahostcomputerorafileserver.Thehostcomputermaintainsitscontrolbyaskingwhethereachconnecteddevicehasmessagestosend.Oneadvantageofthestarnetworkisthatseveraluserscanshareresourcesonacentralhostcomputer(Figure10-2).Inabusnetwork,thereisnohostcomputer,andinsteadeachdeviceinthenetworkhandlesitsowncommunicationcontrol.Allcommunicationstravelalongacommonconnectingcablecalledabusandastheinformationpassesalongthebus,eachdeviceexaminestoseeiftheinformationisintended.*,WhatisaNetwork?,Thisarrangementiscommonforsharingdatastoredondifferentmicrocomputersbutnotasefficientasthestarnetworkforsharingcommonresources(SeeFigure10-3).,Figure10-1Figure10-2Figure10-3,WhatisaNetwork?,Inaringnetwork,eachdeviceisconnectedtotwootherdevices,formingaring.Thereisnocentralcomputerorfileserver.Messagesarepassedaroundtheringuntiltheyreachthecorrectdestination.Withmicrocomputers,theringarrangementistheleastfrequentlyusedofthefournetworks.Itisoftenusedtolinkmainframecomputers,especiallyoverwidegeographicalareas(SeeFigure10-4).*Thehierarchicalnetworkconsistsofseveralcomputerslinkedtoacentralhostcomputer,justlikeastarnetwork,buttheseothercomputersarealsohoststoothersmallercom-puters.Ahierarchicalnetworkisusefulincentralizedorganizations.*Forexample,differentdepartmentswithinanorganizationmayhaveindividualmicrocomputersconnectedtodepartmentalminicomputersandtheminicomputersinturnmaybeconnectedtothecorporationsmainframe,whichcontainsdataandprogramsaccessibletoall(SeeFigure10-5).,WhatisaNetwork?,Figure10-4Figure10-5,WhatisaNetwork?,Figure10-6Geographically,usingbothcableandairconnections,networksrangefromhometocitywideandeveninternational.Hereletushavesomeideaofthreetypes:localareanetworks,metropolitanareanetworks,andwideareanetworks(SeeFigure10-6).Networkswithcomputersandotherdevicesinclosephysicalproximitywithinthesamebuilding,oronthesamecampus,forinstancearecalledlocalareanetworks(LANs).Linkedbycabletelephone,co-axial,orfiber-opticLANsoftenuseabusformoforganization.ALANmaybelinkedtootherLANsortolargernetworks.Figure10-7-2Figure10-7-1AstepupfromtheLANistheMANthemetropolitanareanetwork.Thesenetworksareusedaslinksbetweenofficebuildingsinacity.CellularphonesystemsexpandtheflexibilityofMANsbyallowinglinkstocarphonesandportablephones.WideAreaNetworks(WANs)arecountrywideandworldwidenetworks.Besidescables,theyusemicrowaverelaysandsatellitestoreachusersoverlongdistances.ThewidestofallWANsistheInternet,whichspanstheentireglobe(SeeFigure10-7-1;Figure10-7-2).,WhatisaNetwork?,Notes:1“Thisarrangementiscommonforsharingdatastoredondifferentmicrocomputersbutnotasefficientasthestarnetworkforsharingcommonresources.”本句中，“butnotasefficientasthestarnetworkforsharingcommonresources”等于butthearrangementisnotasefficientasthestarnetworkinregardtosharingcommonresources.本句意为：这种网络结构常见于相互间分享存储于不同微机上的信息，对于公有信息共享效率不如星型网络。2“Thehierarchicalnetworkconsistsofseveralcomputerslinkedtoacentralhostcomputer,justlikeastarnetwork,buttheseothercomputersarealsohoststoothersmallercomputers.”本句中，“consistof”意为：由组成，由构成，“linkedtoacentralhostcomputer”作“severalcomputers”的后置定语，“thesesothercomputers”指除了中心计算机以外的“severalcomputers”.本句意为：树型（分级型）网络由几个计算机连接到一个中央主机上，像星型网络一样，但是这些连网的计算机同时又是其他更小计算机的主机。,WhatisaNetwork?,3“Forexample,differentdepartmentswithinanorganizationmayhaveindividualmicrocomputersconnectedtodepartmentminicomputersandtheminicomputersinturnmaybeconnectedtothecorporationsmainframe,whichcontainsdataandprogramsaccessibletoall.”本句中，“inturn”意为：按次序，依次。“which”引导的非限制性定语从句对“thecorporationsmainframe”作补充说明。本句意为：例如，一个公司的各个部门可以让本部门的个人微机连网到部门的主机微机上，部门主机又可以连网到公司的大型主机上，大型主机存有数据和程序供本公司所有连网微机使用。,WhatisaNetwork?,Choosethebestanswertoeachquestionwiththeinformationfromthepassage.1Whatisthestarnetwork?AEachcomputerhandlesitsowncommunicationsalongacommonconnectingcable.BEachcomputerlinkstoacentralunitandiscontrolledbythiscentralunit.CEachcomputerconnectstotwootherdevicesformingacircle.DSmallercomputersconnecttoacentralhost.2Whatisthelocalareanetwork?AItisusedtolinkofficebuildingswithinacity.BItspanscountries,orformsworldwidenetworks.CItconnectsdevicesthatareclosetooneanother,inthesameoffice,forexample.DItislargerthanametropolitanareanetworkandsmallerthantheInternet.,WhatisaNetwork?,3WhichofthefollowingexpressionsistrueabouttheInternet?ATheInternetisthelargestnetworkintheworldandeveryonewhoconnectshiscomputertotheInternetcanshareinformationandmakecommunicationthroughouttheglobe.BTheInternetisjustthewideareanetworkthatspanscountriestoloadinformationanddelivermessages.CTheInternetisanetworkservertocontrolcountlesscomputersandotherdevicesthathaveconnectedtoit.DTheInternetisnotascompetentasWWW(WorldWideWeb)forelectroniccommunications.4Whatisacommunicationsystem?AAnysystemthatcantransmitdatafromonelocationtoanother.BAnelectronicsystemthattransmitsdataovercommunicationlinesfromonelocationtoanother.CCablesthatspanovercountriestosendmessagesfromonelocationtoanother.DAsystemofelectronicsignalssendingandreceivinginformationthroughtelephonelines.,WhatisaNetwork?,GrammarFocus：倒装句及句子种类倒装句：英语中的陈述句一般使用正常语序，即“主语+谓语”。有时由于结构或修辞的需要，将谓语放在主语前面，这就形成了倒装句。倒装句的结构可分为部分倒装和全部倒装。句子种类：1句子按使用目的可分为1）陈述句：说明一个事实或陈述一种看法。2）疑问句：提出问题，有以下4种。a一般疑问句：Canyoufinishtheworkintime?你能及时完成任务吗？b特殊疑问句：Wheredoyoulive?你住那儿？c选择疑问句：Doyouwantteaorcoffee?你是要茶还是要咖啡？d反意疑问句：Hedoesntknowher,doeshe?他不认识她，对不对？3）祈使句：提出请求、建议或命令。4）感叹句：表示说话人惊奇、喜悦、愤怒等情绪。2句子按其结构可以分为1）简单句：只包含一个主谓结构的句子叫简单句。例如：Sheisfondofcollectingstamps.她喜欢集邮。,WhatisaNetwork?,2）并列句：包含两个或两个以上主谓结构的句子叫并列句，句与句之间通常用并列连词或分号来连接。例如：Thefoodwasgood,buthehadlittleappetite.食物很精美，但他却没什么胃口。（主）（谓）（主）（谓）3）复合句：包含一个主句和一个或几个从句的句子叫复合句，从句由从属连词引导，例如：Thefilmhadbegunwhenwegottothecinema.我们到达电影院的时候，电影已经开演了。主句从句,WhatisaNetwork?,Pointoutthetypesofthefollowingsentences.1“Didhestudymuch?”2Whosgoingtolookafterher?3Tompushedbackhischairasquietlyaspossiblegatheringuphispadandpencilashebackedawayfromthetable.4ShallIdoitorwillyoudoityourself?5Comeon,heresourbus.Letsgoontop.6Really!Idontbelieveit.7“Oh,Lucy,”sheburstout,afterkissingher,“YoullstaywithTomandme,wontyou?”8Nancyfindingmypassportintherefrigerator!9Dontgonearit!10Aswedrovealong,myspiritsrevivedagain.,WhatisaNetwork?,Pointoutthetypesofinterrogativesentences.1Doesshehavesisters?2Herfamilyoncelivedthere,didntthey?3Whichwayareyougoinghome,Tom?4Issheintownorhasshegoingtothecountry?5Canyoutype?6Ishemarriedorsingle?7Youdontthinkwehavelostourway,doyou?8Wheredoyousailfrom?9Areyouhappyoverhere,ordoyoutogobacktoFrance?10Whydidntyouspeaktomyfatheryourselfontheboat?,WhatisaNetwork?,TextinChinese：网络通过电子通信系统，你的计算机能够连接世界范围内的其他计算机，连接因特网和更大型的计算机。电子通信系统通过有线和无线通信线路在世界各地间传输信息。这样的电子通信线路称为网络。网络可以安排成几种不同的连接方式，称为网络结构或拓扑。4种主要的网络结构有：星型、总线型、环形、树型或分级型。星型网络由许多小型计算机或外围设备连接到一个中央单元（主机或文件服务器）。主机进行总控制，询问每个连网的计算机是否有信息要传递。星型网络的一大优势是几个用户可以共享中央主机的资源。在总线型网络中，没有主机，连网的每个设备处理自己的通信。所有通信沿着同一个总线电缆传输，随着信息沿着总线传输，每个设备都在检索需要的信息。这种网络结构常用于相互间分享存储在不同微机上的信息，但是对于公有信息共享效率不如星型网络。环型网络中，每个设备与另外两个设备连接，形成一个环。环型网络没有主机或文件服务器。信息绕着环网传输直到到达正确的目的地。对于微型计算机，环网是4种网络连接中最少使用的类型。环网经常用于连接大型计算机，特别适于地理跨度大的网络。,WhatisaNetwork?,树型网络由几个计算机连接到一个中央主机上，像星型网络一样，但是这些连网的计算机同时又是其他更小的计算机的主机。树型网络多应用于集中的组织团体中。例如，一个公司的各个部门可以让本部门的个人微机连网到部门的主机微机上，部门主机又可以连网到公司的大型计算机主机上，大型主机存有数据和程序供本公司所有连网微机使用。地域上讲，使用有线和无线连接的网络覆盖范围可从一个城市到全世界。这里简介三种网络覆盖类型：局域网、城域网和广域网。连网的计算机和其他设备地理分布临近，例如在一个建筑内，或某一大学校园内，这样的网络称作局域网。局域网由电缆（电话线、co-axial或光纤）连接，常采用总线连接结构。局域网可以连接到其他局域网或大型网络上。城域网规模大于局域网，用于连接一个城市内的各个办公楼区。移动电话系统利用局域网，开通汽车电话和手机业务。广域网指国家或世界范围的网络。广域网除了使用电缆连接外，还使用微波传递和卫星传递到达远程的用户。最广泛使用的广域网就是覆盖全球的因特网了。,WhatisaNetwork?,ReadingSelection:AHome(Page)ofYourOwnInthe60s,peopleaskedaboutyourastrologicalsign.Inthe90s,theywanttoknowyourURL.Thesedays,havingawebaddressisalmostasimportantasastreetaddress.YourWebsiteisanelectronicmeetingplaceforyourfamily,friendsandpotentially*,millionsofpeoplearoundtheworld.Buildingyourdigitaldomaincanbeeasierthanyoumaythink.Bestofall,youmaynothavetospendacent.TheWebbrimswithallkindsoffreeservices,fromtoolstohelpyoutobuildyoursite,tofreegraphics,animationandsitehosting.Allittakesissometimeandcreativity.ThinkofyourhomepageasthestartingpointofyourWebsite.Likethetableofcontentsofabookormagazine,thehomepageisthefrontdoor.Yoursitecanhaveoneormorepages,dependingonhowyoudesignit.Ifthereisntalotofinformationjustyet,yoursitewillmostlikelyhaveonlyahomepage.Butthesiteissuretogrowovertime.WhileWebpagesvarydramaticallyintheirdesignandcontent,mostuseatraditionalmagazinelayout.Atthetopofthepageisabannergraphic.Nextcomesagreetingandashortdescriptionofthesite.Pictures,text,andlinkstootherWebsitesfollow.,WhatisaNetwork?,Ifthesitehasmorethanonepage,therestypicallyalistofitemssimilartoanindexoftenwithabriefdescription.TheitemsinthelistlinktootherpagesontheWebsite.Sometimestheselinksarehighlightedwordsinthebodyofthetext.Itcanalsobeacombinationofboth.Additionally,aWebpagemayhaveimagesthatlinktoothercontent.Beforeyoustartbuildingyoursite,dosomeplanning.Thinkaboutwhomthesiteisforandwhatyouwanttosay.Next,gatherupthematerialthatyouwanttoputonthesite:writethecopy,scanthephotos,designorfindthegraphics.Drawaroughlayoutonasheetofpaper.Whiletherearenorulesyouhavetofollow,thereareafewthingstokeepinmind.Startsimply:Ifyouaretooambitiousatthebeginning,youmaynevergetthesiteofftheground.Youcanalwaysaddtoyoursite.Lessisbetter:Mostpeopledontliketoreadalotoftextonline.Breakitintosmallchunks.,WhatisaNetwork?,Userestraint:Althoughyoucanusewildcolorsandimagesforthebackgroundofyourpages,makesureyourvisitorswillbeabletoreadthetexteasily.Smallerisbetter:MostpeopleconnecttotheInternetwithamodem.Sinceitcantakealongtimetodownloadlargeimagefiles,keepthefilesizessmall.Havetherights:Dontputanymaterialonyoursiteunlessyouaresureyoucandoitlegally.Nowitstimetorollupyoursleevesandstartbuilding.LearntheNetCommunitiesprovidestoolstohelpyoutobuildyoursite,freeWebhosting,andacommunityofotherhomesteaders.,WhatisaNetwork?,科技英语翻译方法与技巧（）英语中句型的翻译1被动语态被动语态是科技语体特点之一。在科技英语文献中，会经常碰到的语法现象。下面简要介绍一下如何正确地理解和翻译这种句子。1）将原有的被动句译成汉语的被动句若当英语被动句在语义上着重谓语动词本身的意义，可直接用汉语被动结构来翻译。例如：ThetelephonewasinventedbyGrahamBell.电话为葛雷姆贝尔发明。Aswithordinaryalgebra，theoperatorsymbo1()canbeomitted正如普通代数一样，运算符()可被省略。,WhatisaNetwork?,2）将被动句译成汉语的主动句汉语的被动句没有英语被动句运用得广泛。在翻译英语被动句时，可在保持原文意思不变的基础上，根据句子整体结构将被动句转换成汉语的主动句进行翻译。被动句转译成汉语的主动句关键是如何确定汉语主动句的主语。一般有以下几种方法：被动句不含动作执行者，可加入“有人，大家，人们，我们”等。例如：Awomanwasheardmoaningaftermidnight.有人在深夜听到一女人呻吟。但被动句中的动作承受对象含有物主代词，可根据物主代词所表示的人称来确定译句的主语。例如：Beingaskedtogiveaperformance,shecouldnotrefuse.大家请她表演个节目，她不能拒绝。Ourcalculationmustbecheckedandrechecked.我们必须把数字再核对几次。,WhatisaNetwork?,当被动句含有by短语时，只要不违反原文意思，并又更能合乎中文语法，可直接将by短语改做主语。例如：Englishisspokenbymanypeople.许多人讲英语。Largequantitiesoffuelareusedbymodernindustry.现代工业耗用大量燃料。当原被动结构在语义上表示义务时，可直接译成汉语的主动句。例如：Themattermustbeinvestigatedcarefully.这件事应仔细调查。当被动结构的谓语在语义上接近不及物动词时，可直接译成汉语的主动句。例如：Troopsweredismissedwhentheparadewasover.游行结束后，队伍就解散了。,WhatisaNetwork?,3）将被动句译成汉语的无主句当遇到不带by的短语，并含有情态动词的英语被动句时，我们可以转译成汉语的无主句。例如：Thereforelogicmustbeusedwhenmakingdecisions，orwhencalculatingorprocessingdata因此，在做判定或者计算或处理数据时，必须采用逻辑。Lifecantbeunderstoodwithoutmuchcharity.没有爱心，就无法了解生活。4）固定译法科技英语中有不少常用的被动结构，已经有了习惯译法。例如：Itshouldbepointedoutthat应当指出ItshouldbeObviousthat很明显Itisveryimportantthat是很重要的Itissaidthat据说,WhatisaNetwork?,2非谓语动词在英语中，动词可分为限定动词和非限定动词两大类。限定动词在句子中做谓语，它受到主语的限制。而非限定动词在句子中不能独立作谓语，但可以和助动词或情态动词等构成谓语，还可以在句中充当主语、宾语、定语、状语等。因此，非限定动词的句子复杂些，翻译时有一定的难度。这里，就非限定动词的若干翻译技巧做一些探讨。非限定动词有三种形式：1）不定式（theInfinitive）不定式在科技文章中用的很多,它是一种非限定形式，通常前面带有小品词“to”，有时也可不带“to”。它在句中做主语、宾语、表语、定语、状语等。翻译成中文时应根据其在句子中所起的作用及上下文，而“酌情”予以翻译。例如：Toignorethiswouldbeamistake.忽视这一点是错误的。（做主语）Itonlytookusayeartocompletethework.完成这个工作只花了我们一年时间。（间接做主语）在许多情况下，常常用代词“it”来带做主语，这是为了使句子比较平稳。这种结构在科技文献中是经常出现的。,WhatisaNetwork?,Ididntthinktofindyouhere.没想到在这儿碰到你。（做宾语）Ithinkitbettertotranslateitthisway.我觉得这样译更好些。（间接做宾语）Effortstostandardizehigh-levellanguagesandcompilershavereceivedmuchattentioninrecentyears.使高级语言及编译程序标准化的努力，近年来已经受到人们的很大关注。（做定语）不定式做定语时一般放在它所修饰的名词后面。可译成“的”。Hisjobistocleantheclassroom.它的工作是打扫教室。（做表语）Tocreatedifferentcolors，theintensityofeachofthethreeelectronbeamsisvaried.（做状语）为了生成不同的颜色，三种电子束中的每一种的强度均是可变的。Computerscanconnecttothesenetworkstouseresourcesinanothercityorcountry.（做状语）计算机可以连接到这些网络上，以便使用另一城市或另一国家的资源。动词不定式作目的状语时可译成“为了”，“以便”等。但有时不太容易看出，需根据上下文来判断。一般放在句首，译为“为了”；放在句末，译为“以便”。,WhatisaNetwork?,2）动名词动名词是一种非限定动词，它在句中起名词作用，也可以用来构成名词。但它具有动词的若干性质，在句中用做主语、表语和宾语等。例如：DevelopinganLSIcircuitrequiresagreatdealofengineeringresearchanddevelopment开发大规模集成电路需要大量的工程研究和工程发展工作。（做主语）Therealproblemisgettingtoknowtheinstructionsofusingthecomputer.真正的问题是了解使用计算机的指令。（做表语）TheRAMcapacitycansometimesbeexpandedbyaddingextrachipsRAM的容量有时可以通过附加额外的芯片来加以扩展。（做宾语）,WhatisaNetwork?,3）分词分词在科技英语文章中也是一种很常见的语法现象，它有两种形式：现在分词和过去分词。它主要起形容词和副词作用。一般地说，分词短语在句子中所起的具体作用为表语、定语、状语等等。例如：Helookeddisappointed.他显得很失望。（做表语）Barkingdogsseldombite.爱叫的狗很少咬人。（做定语）Workinginthebackground，theoperatingsystemmanages，coordinates，andcontrolsthecomputerhardware，inputandoutputtasks，andstoragesystem.在此背景下工作时，操作系统管理、协调及控制计算机的硬件、输入及输出任务，以及存储系统。（做状语）,WhatisaNetwork?,Translatethepassage.Moderncomputersareoftendesignedasarelatedseriessothateachprocessorintheseriesiscompatiblewiththeothers.Compatibilityisadesigntechniquewhichenablesanypripheraldevicetobeconnectedtoanyprocessorintheseriesandwhichalsoenablescommonorderorinstructioncodestobeusedonanyprocessorwithoutalteration.Thisallowsflexibilityinthechoiceofconfigurationtosurtvaryingcircumstancesandenablesamorepowerfulprocessortobeusedwithoutreprogrammingorchangeofperipherals.Thetermalsorelatestothecompatibilityofpackageprogramsforspecificmodelsofcomputers.Packagesareusuallydevelopedforparticularmodelsandmayneedtobemodifiedtobecompatiblewithothermodels.,WhatisaNetwork?,PracticalWriting：标点符号在谈话的时候，我们靠停顿和语顿把我们的意思表示得更清楚。如果我们想在写作中更清楚地表达思想内容，就必须依靠标点符号。每个标点符号都有它的意义，如果把标点符号点错了的话，就有可能改变句子的意义或引起误解。1）句号、问号、感叹号：主要用在句子末尾，表示较长的停顿。2）逗号：用在句子当中，表示一个短促的停顿；还可以用来连接一个句子中的平行成分。3）冒号：在用于列举的东西前面，引用的句子的前面及附加的解释性的分句前面。4）破折号：主要在解释性的插入语的前面和后面，总括前面列举的若干东西等。5）引号：主要用来表示中间包入的成分是一句引语。6）括号：用来表示里面的东西是一个插入的或附加的解释成分。7）省略号、连字号：主要是在一个词的内部的符号。,WhatisaNetwork?,Punctuatethefollowingsentences.1Loverswalkhandinhandintheparkpayingnoattentiontopeoplearound.2Theworkerwasverytiredfromhisworkandhecouldntgoonwithoutagoodsleep.3LiPingisagoodstudentalthoughhefailedinchemistryandbarelypassedmathematics.4ShehadthreearticlespublishedinthreepopularmagazinesTVGuideReadersDigestandWomansDay.5OneofmyfriendsaskedwhatdidtheymeanwhentheysaidWewontbuythestory.6FinishthereportbyThursdaysaidthemanagerifyoufinishearlyyoucantakeFridayoff.7OhDearwhatareyoudoingontheroof.8TheSmithsnewhouseisnotfarfromtherailwaystation.9IrealizedatoncethatsomethingwaswrongIwasnothowevertheonlypersonwhowasconcerned.10Tobeornottobethatisthequestion.Hamlet.,WhatisaNetwork?,Punctuatethefollowingsentences.1Loverswalkhandinhandintheparkpayingnoattentiontopeoplearound.2Theworkerwasverytiredfromhisworkandhecouldntgoonwithoutagoodsleep.3LiPingisagoodstudentalthoughhefailedinchemistryandbarelypassedmathematics.4ShehadthreearticlespublishedinthreepopularmagazinesTVGuideReadersDigestandWomansDay.5OneofmyfriendsaskedwhatdidtheymeanwhentheysaidWewontbuythestory.6FinishthereportbyThursdaysaidthemanagerifyoufinishearlyyoucantakeFridayoff.7OhDearwhatareyoudoingontheroof.8TheSmithsnewhouseisnotfarfromtherailwaystation.9IrealizedatoncethatsomethingwaswrongIwasnothowevertheonlypersonwhowasconcerned.10Tobeornottobethatisthequestion.Hamlet.,WhatisaNetwork?,Punctuatethefollowingsentences.1Loverswalkhandinhandintheparkpayingnoattentiontopeoplearound.2Theworkerwasverytiredfromhisworkandhecouldntgoonwithoutagoodsleep.3LiPingisagoodstudentalthoughhefailedinchemistryandbarelypassedm