《计算机专业英语》课件第3章

Unit3SoftwareSystemofComputer

教学目标教学内容教学目标了解系统软件的概念以及常见的操作系统了解应用软件的概念及其特性了解计算机语言的发展掌握数据结构的基本理论掌握关系数据库的相关理论了解多媒体的基本知识了解人工智能的基本理论教学内容Text1SystemsoftwareText2ApplicationSoftwareText3ComputerLanguagesText4DataStructuresText5OperatingSystemsText6StructureoftheRelationaldatabaseText7MultimediaText8SoftwareengineeringText9IntroductiontoWindowsText10ArtificialIntelligenceText1SystemsoftwareMainContentsWordsandExpressionsExercisesSoftwareSoftwarereferstocomputerprograms.Programsaretheinstructionsthattellthecomputerhowtoprocessdataintotheformyouwant.Therearetwokindsofsoftware:systemsoftwareandapplicationsoftware.Systemsoftwareisacollectionofprogramsthatenablesapplicationsoftwaretorunonacomputersystem'shardwaredevices,itisbackgroundsoftwareandincludesprogramsthathelpthecomputermanageitsowninternalresources.Applicationsoftwareisaspecializedprogramsthatenablestheusertoaccomplishspecifictasks.SystemsoftwareSystemsoftwareconsistsoffourkindsofprograms:bootstraploader,diagnosticroutines,basicinput-outputsystem,andoperatingsystem.Amongthesefourparts,theoperatingsystemiswemostconcernedwith,whichhelpsmanagecomputerresources.Mostimportantoperatingsystemsare:Windows,WindowsNT,OS/2,Macintosh,andUnix.Windows

Windowsgetsitsnamebecauseofitsabilitytorunmultipleapplicationsatthesametime,eachinitsownwindow.Windowsoffersgraphicaluserinterface(GUI),presentstheuserwithgraphicimagesofcomputerfunctionsanddata.Itprovidesastandardmechanismforcopyingormovinginformationfromoneprogramtoanother.Thismechanism,calledtheclipboard,meansthatinformationcreatedinonecontextisinstantlyreusableinanother,youdon'tneedtoreenterinformationorworkwithclumsydata-transferutilities.WindowsalsohasDDE(dynamicdataexchange)andOLE(objectlinkingandembedding)functions.InDDEtwoormoreapplicationscanbelinked.Thisway,datacreatedinoneapplicationisautomaticallyenteredintotheothers.OLE,likeDDE,linksdatabetweenapplications.Additionally,OLEallowstheapplicationreceivingthedatatodirectlyaccesstheapplicationthatcreatedthedata.

WindowsNTWindowsNTisanoperatingsystemdesignedtorunonawiderangeofpowerfulcomputersandmicrocomputers.Itisaverysophisticatedandpowerfuloperationsystem.DevelopedbyMicrosoft,WindowsNTisnotconsideredareplacementforWindows.Rather,itisanadvancedalternativedesignedforverypowerfulmicrocomputersandnetworks.WindowsNThastwomajoradvantageswhencomparetoWindows:MultiprocessingItissimilartomultitaskingexceptthattheapplicationsarerunindependentlyatthesametime.Forinstance,youcouldbeprintingawordprocessingdocumentandusingadatabasemanagementprogramatthesametime.Withmultitasking,thespeedatwhichthedocumentisprintedisaffectedbythedemandsofthedatabasemanagementprogram.Withmultiprocessing,thedemandsofthedatabasemanagementprogramdonotaffecttheprintingofthedocument.NetworkingInmanybusinessenvironments,workersoftenusecomputertocommunicatewithoneanotherandtosharesoftwareusinganetwork.Thisismadepossibleandcontrolledbyspecialsystemsoftware.WindowsNThasnetworkcapabilitiesandsecuritychecksbuiltintotheoperatingsystem.Thismakesnetworkinstallationanduserelativelyeasy.OS/2OS/2wasdevelopedjointlybyIBMandMicrosoftCorporation.OS/2hasmanysimilaritieswithWindowsNT.Itisdesignedforverypowerfulmicrocomputersandhasseveraladvancedfeatures.SomeofitsadvantagesoverWindowsNTinclude:MinimumsystemconfigurationLikeWindowsNT,OS/2requiressignificantmemoryandharddiskspace.However,OS/2requiresslightlyless.WindowsapplicationLikeWindowsNT,OS/2doesnothavealargenumberofapplicationprogramswrittenespeciallyforit.OS/2canalsorunWindowsprograms,butitrunstheseprogramsslightlyfasterthanWindowsNT.CommonuserinterfaceMicrocomputerapplicationprogramswrittenspecificallyforWindowsNT,aswellasforOS/2,haveconsistentgraphicsinterfaces.Acrossapplications,theuserisprovidedwithsimilarscreendisplays,menus,andoperations.Additionally,OS/2offersaconsistentinterfacewithmainframes,minicomputers,andmicrocomputers.MacintoshOperationSystemTheMacintoshSoftware,whichrunsonlyonMacintoshcomputers,offersahigh-qualitygraphicaluserinterfaceandisveryeasytouse.AppleMacintoshSystem7.5designedforApplecomputersusingMotorola'sPowerPCmicroprocessor,isasignificantmilestoneforApple.ItisaverypowerfuloperatingsystemlikeWindowsNTandOS/2.System7.5hasnetworkcapabilitiesandcanreadWindowsandOS/2files.Ithasseveraladvantages:EaseofuseThegraphicaluserinterfacehasmadetheMacintoshpopularwithmanynewcomerstocomputing.Thisbecauseitiseasytolearn.QualitygraphicsMacintoshOperationSystemMacintoshhasestablishedahighstandardforgraphicsprocessing.ThisisaprincipalreasonwhytheMacintoshispopularfordesktoppublishing.Usersareeasilyabletomergepictorialandtextmaterialstoproducenearlyprofessional-lookingnewsletters,advertisements,andthelike.ConsistentinterfacesMacintoshapplicationshaveaconsistentgraphicsinterface.Acrossallapplications,theuserisprovidedwithsimilarscreendisplays,menus,andoperations.MultitaskingLikeWindows,WindowsNT,andOS//2,theMacintoshSystemenablesyoutodomultitasking.Thatis,severalprogramscanrunatthesametime.CommunicationsbetweenprogramsTheMacintoshsystemallowsapplicationsprogramstosharedataandcommandswithotherapplicationsprograms.UnixUnixwasoriginallydevelopedbyAT&Tforminicomputersandisverygoodformultitasking.Itisalsogoodfornetworkingbetweencomputers.UnixinitiallybecamepopularinindustrybecauseformanyyearsAT&Tlicensedthesystemtouniversitiesforanominalfee.Itispopularamongengineersandtechnicalpeople,withthearrivalofverypowerfulmicrocomputers,Unixisbecomingalargerplayerinthemicrocomputerworld.Unixcanbeusedwithdifferenttypesofcomputersystems,thatis,itisaportableoperatingsystem.Itisusedwithmicrocomputers,minicomputers,mainframes,andsupercomputers.Theotheroperatingsystemsaredesignedformicrocomputersandarenotnearlyasportable.Italsohastheadvantagesofmultitasking,multiprocessing,multiuser,andnetworking.WordsandExpressionssystemsoftware系统软件applicationsoftware应用软件accomplish[ə'kʌmpliʃ;ə'kʃm-]vt.达到(目的)；完成(任务、使命、计划、事业等)；实现(诺言、计划等)：diagnosticroutines【计算机】诊断(例行)程序[亦作diagnosticsubroutine,diagnostictest]basicinput-outputsystem基本输入输出系统operatingsystem操作系统graphicaluserinterface(GUI)图形用户界面mechanism['mekənizəm]n.机械,机构,结构机制，原理reenter[,ri:'entə]vt.再进入；重返OLE(objectlinkingandembedding)functions对象连接与嵌入功能DDE(dynamicdataexchange)动态数据交换clipboard[‘klipbʃ:d]n.剪贴板WordsandExpressionssophisticated[sə'fistikeitid]adj.（系统、流程、技术等)极其复杂的，精密的，尖端的，发达的replacement[ri'pleismənt]n.交换,更换,代替者21世纪大英汉词典》

alternative[ɔ:l'tə:nətiv]adj.1.两者(或两者以上)择一的，二择其一的，可从数个中任择其一的；(两种选择中)非此即彼的2.供替代的；供选择的3.(两者)互斥的independently[indi'pendəntli]adv.独立地,自立地milestone['mailstəun]n.里程碑merge[mə:dʒ]vt.【计算机】合并pictorial[pik'tʃ:riəl]adj.1.图片的；用图片表示的；由图片组成的；2.形象化的；生动的newsletters['nju:z,letə(r)]n.时事通讯,时事分析,时事传报21世纪大英汉词典》

AT&T美国电话电报公司(财富500强公司之一，总部所在地美国,主要经营电讯)portable['pɔ:təbl]adj.【计算机】可移植的，不经修改便可在任何计算机上使用的multiprocessing[,mʌlti'prəusesiŋ;-'prʃ-]n.【计算机】多重处理(使用两个以上通往同一记忆系统的电脑处理机，能同时处理多项程序)，多道处理ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Systemsoftwareisaspecializedprogramsthatenablestheusertoaccomplishspecifictasks.（）2.Theoperatingsystemhelpsmanagecomputerresources.（）3.Windowsgetsitsnamebecauseofitsabilitytorunmultipleapplicationsatthesametime,eachinitsownwindow.（）4.WindowsalsohasDDE(dynamicdataexchange)andOLE(objectlinkingandembedding)functions.（）5.OLEdon’tallowtheapplicationreceivingthedatatodirectlyaccesstheapplicationthatcreatedthedata.（）6.Withmultiprocessing,thedemandsofthedatabasemanagementprogramdoaffecttheprintingofthedocument.（）7.WindowsNThasnetworkcapabilitiesandsecuritychecksbuiltintotheoperatingsystem.Thismakesnetworkinstallationanduserelativelyeasy.（）8.OS/2wasdevelopedonlybyMicrosoftCorporation.（）9.TheMacintoshSoftware,whichrunsonlyonMacintoshcomputers,offersahigh-qualitygraphicaluserinterfaceandisveryhardtouse.（）10.UnixwasoriginallydevelopedbyAT&Tforminicomputersandisverygoodformultitasking.ExercisesII.Fillintheblankswithproperwords.1.Softwarereferstocomputerprograms.__________aretheinstructionsthattellthecomputerhowtoprocessdataintotheformyouwant.2.Therearetwokindsofsoftware:systemsoftwareand__________software.3.__________softwareisacollectionofprogramsthatenablesapplicationsoftwaretorunonacomputersystem'shardwaredevices,itisbackgroundsoftwareandincludesprogramsthathelpthecomputermanageitsowninternalresources.4.__________softwareconsistsoffourkindsofprograms:bootstraploader,diagnosticroutines,basicinput-outputsystem,andoperatingsystem.5.Windowsoffers__________,presentstheuserwithgraphicimagesofcomputerfunctionsanddata.6.LikeWindows,WindowsNT,andOS//2,theMacintoshSystemenablesyoutodo__________Thatis,severalprogramscanrunatthesametime.7.Unixisbecomingalargerplayerinthemicrocomputerworld.Unixcanbeusedwithdifferenttypesofcomputersystems,thatis,itisaportableoperatingsystem.Itisusedwithmicrocomputers,minicomputers,__________,andsupercomputers.Text2ApplicationSoftwareMainContentsWordsandExpressionsExercisesApplicationsoftwareApplicationsoftwaremightbedescribedasend-usersoftware.Applicationsoftwareperformsusefulworkongeneral-purposetaskssuchaswordprocessingandcostestimating.Therearecertaingeneral-purposeprogramsthatarewidelyusedinnearlyallcareerareas.Theyarewordprocessing,electronicspreadsheets,graphicprogramsandsoon.Theyarealsocalledbasictoolsandhavesomecommonfeatures.InsertPointMenusHelpButtonBarsDialogBoxScrollBarsWYSIWYGFunctionKeysWordprocessingsoftware

Wordprocessingsoftwareisusedtocreate,edit,save,andprintdocuments.Documentscanbeanykindoftextmaterial.Withwordprocessing,youviewthewordsyoutypeonamonitorinsteadofonapieceofpaper.Afteryoufinishyourtyping,saveyourwordsondiskettesorharddisk,andprinttheresultsonpaper.Thebeautyofthismethodisthatyoucanmakechangesorcorrectionsbeforeprintingoutthedocument.Evenafteryourdocumentisprintedout,youcaneasilygobackandmakechanges.Youcanthenprintitoutagain.Wanttochangeareportfromdoublespacedtosinglespaced?Alterthewidthofthemarginsontheleftandright?Deletesomeparagraphsandaddsomeothersfromyetanotherdocument?Awordprocessorallowsyoutodoallthesewithease.Indeed,deleting,inserting,andreplacing—theprincipalcorrectingactivities—canbedonejustbypressingkeysonthekeyboard.PopularwordprocessingsoftwareareWord,WPSandsoon.Theyhavesomecommonfeatures.WordWrapandtheEnterKeyOnebasicwordprocessingfeatureiswordwrap.Whenyoufinishaline,awordprocessordecidesforyouandautomaticallymovestheinsertionpointtothenextlines.Tobeginanewparagraphorleaveablankline,youpresstheEnterkey.SearchandReplaceAsearchorfindcommandallowsyoutolocateanycharacter,word,orphraseinyourdocument.Whenyousearch,theinsertionpointmovestothefirstplacetheitemappears.Ifyouwant,theprogramwillcontinuetosearchforallotherlocationswheretheitemappears.Thereplacecommandautomaticallyreplacesthewordyousearchforwithanotherword.Thesearchandreplacecommandsareusefulforfindingandfixingerrors.Cut,Copy,andPasteWithawordprocessor,youselecttheportionoftexttobemovedbyhighlightingit.Usingeitherthemenuorbuttonbar,choosethecommandtocuttheselectedtext.Theselectedtextdisappearsfromyourscreen.Thenmovetheinsertionpointtothenewlocationandchoosethepastecommandtoreinsertthetextintothedocument.Inasimilarmanner,youcancopyselectedportionsoftextfromonelocationtoanother.SpreadsheetAspreadsheetisanelectronicworksheetusedtoorganizeandmanipulatenumbersanddisplayoptionsforanalysis.Spreadsheetsareusedbyfinancialanalysts,accountants,contractors,andothersconcernedwithmanipulatingnumericdata.Spreadsheetsallowyoutotryoutvarious"what-if"kindsofpossibilities.Thatisapowerfulfeature.Youcanmanipulatenumbersbyusingstoredformulasandcalculatedifferentoutcomes.

Aspreadsheethasseveralparts.Theworksheetareaofthespreadsheethaslettersforcolumnheadingsacrossthetop.Italsohasnumbersforrowheadingsdowntheleftside.Theintersectionofacolumnandrowiscalledacell.Thecellholdsasingleunitofinformation.Thepositionofacelliscalledthecelladdress.Forexample,"A1"isthecelladdressofthefirstpositiononaspreadsheet,thetopmostandleftmostposition.Acellpointer—alsoknownasthecellselector—indicateswheredataistobeenteredorchangedinthespreadsheet.Thecellpointercanbemovedaroundinmuchthesamewaythatyoumovetheinsertionpointerinawordprocessingprogram.Excelisthemostcommonspreadsheetsoftware.Ithassomecommonfeaturesofspreadsheetprograms.FormatLabelisoftenusedtoidentifyinformationinaworksheet,itisusuallyawordorsymbol.Anumberincelliscalledavalue.Labelsandvaluescanbedisplayedorformattedindifferentways.Alabelcanbecenteredinthecellorpositionedtotheleftorright.Avaluecanbedisplayedtoshowdecimalplaces,dollars,orpercent.Thenumberofdecimalpositionscanbealtered,andthewidthofcolumnscanbechanged.FormulasOneofthebenefitsofspreadsheetsisthatyoucanmanipulatedatathroughtheuseofformulas.Formulasareinstructionsforcalculations.Theymakeconnectionsbetweennumbersinparticularcells.FunctionsFunctionsarebuilt-informulasthatperformcalculationsautomatically.RecalculationRecalculationorwhat-ifanalysisisoneofthemostimportantfeaturesofspreadsheets.Ifyouchangeoneormorenumbersinyourspreadsheet,allrelatedformulaswillrecalculateautomatically.Thusyoucansubstituteonevalueforanotherinthecellsaffectedbyyourformulaandrecalculatetheresults.Formorecomplexproblems,recalculationenablesyoutostorelong,complicatedformulasandmanychangingvaluesandquicklyproducealternatives.WordsandExpressionsgeneral-purposetasks通用任务wordprocessingn.【计算机】字处理costestimating成本计算electronicspreadsheets电子表单graphicprograms图形程序cursor['kə:sə]n.【计算机】1.(显示器的)光标2.光标移动器，鼠标ablinkingverticalbar闪烁的竖线光标thedirectionalarrowkeys方向键pull-downmenu下拉菜单representation[,reprizen'teiʃən]n.表示法,表现,陈述，答辩Dialogboxes对话栏WordsandExpressionsScrollbars滚动条preview['pri:'vju:]n.事先查看,查阅v.事先查看,查阅diskette['disket]n.【计算机】软(磁)盘，塑料磁盘(=floppydisk)margin['mɑ:dʒin]n.(时间,金钱)富余,利润,页边空白,边缘cut[kʌt]n.【计算机】剪切copy['kɔpi]n.【计算机】复制paste[peist]n.【计算机】粘贴highlighting['hai,laitiŋ]n.加亮formulas['fɔ:mjulə]n.公式,配方,规则；婴儿食品calculations[,kælkju'leiʃən]n.计算recalculate[ri'kælkjuleit]vt.再计算(再核算,再估计,换算)substitute['sʌbstitju:t]n.代替者,代用品v.代替vi.(for)代替vt.用...代替,代以ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Youcannotmovetheinsertpointaroundusingamouseorthedirectionalarrowkeysonmanykeyboards.（）2.Scrollbarsenableyoutodisplayadditionalinformationnotcurrentlyvisibleonthescreen.（）3.ApplicationprogramswithoutWYSIWYGcanalwaysdisplayanexactrepresentationofthefinalprinteddocument.（）4.Functionkeysdoidenticalthingsindifferentsoftwarepackages.（）5.Whenyousearch,theinsertionpointmovestothefirstplacetheitemappears.Ifyouwant,theprogramwillcontinuetosearchforallotherlocationswheretheitemappears.（）6.Aspreadsheetisanelectronicworksheetusedtoorganizeandmanipulatenumbersanddisplayoptionsforanalysis.（）7.Oneofthebenefitsofspreadsheetsisthatyoucanmanipulatedatathroughtheuseofformulas.Formulasareinstructionsforcalculations.Theymakeconnectionsbetweennumbersinparticularcells.ExercisesII.Fillintheblankswithproperwords.1.Theinsertpointor__________showsyouwhereyoucanenterdatanext.2.Typically,themenusaredisplayedinamenu__________atthetopofthescreen.3.__________standsfor“WhatYouSeeIsWhatYouGet.”4.TheWYSIWYGfeatureallowstheusertopreviewthedocument'sappearance__________itisprintedout.5.With__________processing,youviewthewordsyoutypeonamonitorinsteadofonapieceofpaper.6.A__________orfindcommandallowsyoutolocateanycharacter,word,orphraseinyourdocument.7.The__________commandautomaticallyreplacesthewordyousearchforwithanotherword.Thesearchandreplacecommandsareusefulforfindingandfixingerrors.8.Usingeitherthemenuorbuttonbar,choosethecommandtocuttheselectedtext.Theselectedtextdisappearsfromyourscreen.Thenmovetheinsertionpointtothenewlocationandchoosethe__________commandtoreinsertthetextintothedocument.9.__________orwhat-ifanalysisisoneofthemostimportantfeaturesofspreadsheets.Ifyouchangeoneormorenumbersinyourspreadsheet,allrelatedformulaswillrecalculateautomatically.Text3ComputerLanguagesMainContentsWordsandExpressionsExercisesProgramminglanguagesProgramminglanguagesdatebackalmosttotheinventionofthedigitalcomputerinthe1940s.Computerlanguageshaveundergonedramaticevolutionsincethefirstelectroniccomputerswerebuilt.Earlyon,programmersworkedwiththemostprimitivecomputerinstructions—machinelanguage.Theseinstructionswererepresentedbylongstringsofonesandzeroes.Thefirstassemblylanguagesemergedinthelate1950swiththeintroductionofcommercialcomputers.Itmapsmachineinstructionstohuman-readablemnemonics,suchasADDandMOV.Computerprogrammersuseassemblylanguagestomakemachine-languageprogramseasiertowrite.Thefirstprocedurallanguagesweredevelopedinthelate1950stoearly1960s:FORTRAN,createdbyJohnBackus1,andthenCOBOL,createdbyGraceHopper.ThefirstfunctionallanguagewasLISP,writtenbyJohnMcCarthyinthelate1950s.Althoughheavilyupdated,allthreelanguagesarestillwidelyusedtoday.Inthelate1960s,thefirstobject-orientedlanguages,suchasSIMULA,emerged.Logiclanguagesbecamewellknowninthemid1970swiththeintroductionofPROLOG3,alanguageusedtoprogramartificialintelligencesoftware.Duringthe1970s,procedurallanguagescontinuedtodevelopwithALGOL,BASIC,PASCAL,C,andAda.SMALLTALK6wasahighlyinfluentialobject-orientedlanguagethatledtothemergingofobject-orientedandprocedurallanguagesinC++andmorerecentlyinJAVA.Althoughpurelogiclanguageshavedeclinedinpopularity,variationshavebecomevitallyimportantintheformofrelationallanguagesformoderndatabases,suchasSQL.Intime,higher-levellanguagesevolved,suchasPASCAL,BASIC,COBOL,C,C++,andJAVA.High-levellanguagesarerelativelysophisticatedsetsofstatementsutilizingwordsandsyntaxfromhumanlanguage.Theyaremoresimilartonormalhumanlanguagesthanassemblyormachinelanguagesandarethereforeeasiertouseforwritingcomplicatedprograms.Theproblemsprogrammersareaskedtosolvehavebeenchanging.Today'sprogramsusesophisticated"user-friendlyinterfaces,"involvingmultiplewindows,menus,anddialogboxes.Theprogramswrittentosupportthisnewapproacharefarmorecomplexthanthosewrittenjusttenyearsago.Generally,asprogrammingrequirementshavechanged,bothlanguagesandthetechniquesusedforwritingprogramshaveevolved.WordsandExpressionsundergo[,ʌndə'gəu]v.遭受,经历,忍受evolution[,i:və'lu:ʃən,,evə-]n.进化,发展,进展primitive['primitiv]adj.原始的n.原始人human-readableadj.人可读的mnemonics[ni:'mɔniks]n.记忆术，记忆法assemblylanguage汇编语言correspond[kɔris'pɔnd]v.符合,通信,相当roughly['rʌfli]adv.概略地,粗糙地aid[eid]n.帮助,有帮助的事物v.援助,帮助manipulate[mə'nipjuleit]v.操纵,利用,假造[计算机]操作dot[dɔt]n.点,圆点,小孩子,小东西v.作小点记号,加小点于,点缀[计算机]点procedurallanguage过程语言WordsandExpressionspopularity[,pɔpju'læriti]n.普及,流行variation[,vɛəri'eiʃən]n.变化,变动,变种,变异vitally['vaitəli]adv.与生命有关地,致命地,紧要地syntax['sintæks]n.句法complicated['kɔmplikeitid]adj.复杂的,难懂的approximating[ə'prɔksimit]adj.大约的,近似的v.接近,约等于interpreter[in'tə:pritə]n.译员,口译者compiler[kəm'pailə]编译器,编译程序intermediary[,intə'mi:diəri]n.仲裁者,调解者,媒介物adj.中间的,媒介的[计算机]媒介invoke[in'vəuk]v.[计算机]调用linker['liŋkə]n.[计算机]链接器executable['eksikju:təbl]adj.可执行的spot[spɔt]n.污点,地点,斑点adj.当场的,现实买卖的v.污点,认出,用灯光照射ExercisesI.Trueorfalse?Ifcorrect,writeTinparentheses;Otherwise,writeF.（）1.Earlyon,programmersworkedwiththemostprimitivecomputerinstructions—machinelanguage.Theseinstructionswererepresentedbylongstringsofzeroesandtwos.（）2.Anassemblylanguagestatementiscomposedwiththeaidofeasytoremembercommands.（）3.ThecommandtoaddthecontentsofthestorageregisterAtothecontentsofstorageregisterBmightbewrittenADDA,Binatypicalassemblylanguagestatement.（）4.Assemblylanguagessharecertainfeatureswithmachinelanguages.（）5.Programmersusemachinelanguageswhenitisimportanttominimizethetimeittakestorunaprogram,becausethetranslationfromassemblylanguagetomachinelanguageisrelativelysimple.（）6.Inthelate1960s,thefirstobject-orientedlanguages,suchasFORTRAN,emerged.（）7.High-levellanguagesarelesssimilartonormalhumanlanguagesthanassemblyormachinelanguagesandarethereforeeasiertouseforwritingcomplicatedprograms.（）8.Programswritteninahigh-levellanguagemaytakelongertoexecuteanduseupmorememorythanprogramswritteninanassemblylanguage.（）9.Becausethetime-consumingtaskoftranslatingthesourcecodeintomachinelanguagehasalreadybeenaccomplished,compilersproduceaprogramthatisveryfasteachtimeitisrun.ExercisesII.Fillintheblankswithproperwords.1.Computerprogrammersuseassemblylanguagestomake__________programseasiertowrite.2.__________languagesarealsousedwhensomepartofthecomputerhastobecontrolleddirectly,suchasindividualdotsonamonitorortheflowofindividualcharacterstoaprinter.3.__________languagesarerelativelysophisticatedsetsofstatementsutilizingwordsandsyntaxfromhumanlanguage.4.A__________translatesthecodeintoanintermediaryform.Thisstepiscalledcompiling,andproducesanobjectfile.5.Thecompilertheninvokesa__________,whichturnstheobjectfileintoanexecutableprogram.Text4DataStructuresMainContentsWordsandExpressionsExercisesDataStructuresAsingleintegercanbeveryusefulifweneedacounter,asum,oranindexinaprogram,butgenerallywemustalsodealwithdatathathavelotsofparts,suchasalist.Wedescribethelogicalpropertiesofsuchacollectionofdataasanabstractdatatype;wecalltheconcreteimplementationofthedataadatastructure.Whenaprogram’sinformationismadeupofcomponentparts,wemustconsideranappropriatedatastructure.Datastructureshaveafewfeaturesworthnoting.First,theycanbe“decomposed”intotheircomponentelements.Second,thearrangementoftheelementsisafeatureofthestructurethataffectshoweachelementisaccessed.Third,boththearrangementoftheelementsandthewaytheyareaccessedcanbeencapsulated.Weusethesameapproachtodatastructuresinourprograms.Adatastructureisdefinedby(1)thelogicalarrangementofdataelements,combinedwith(2)thesetofoperationsweneedtoaccesstheelements.Inmodelingdatainaprogram,wewearmanyhats.Thatis,wemustdeterminethelogicalpictureofthedata,choosetherepresentationofthedata,anddeveloptheoperationsthatencapsulatethisarrangement.Duringthisprocess,weconsiderdatafromthreedifferentperspectives,orlevels:1.Application(oruser)level:Awayofmodelingreal-lifedatainaspecificcontext;alsocalledtheproblemdomain.2.Logical(orabstract)level:Anabstractviewofthedatavalues(thedomain)andthesetofoperationstomanipulatethem.3.Implementationlevel:Aspecificrepresentationofthestructuretoholdthedataitems,andthecodingoftheoperationsinaprogramminglanguage(iftheoperationsarenotalreadyprovidedbythelanguage).Withouttellinghowtheoperationswork.Ittellswhatbutnothow.Forinstance,theabstractviewofcheckinginabookcanbesummarizedinthefollowingspecification:Theonlycommunicationfromtheuserintotheimplementationleveloccursintermsofinputspecificationsandallowableassumptions—thepreconditionsoftheaccessingroutines.Theonlyoutputfromtheimplementationlevelbacktotheuseristhetransformeddatastructuredescribedbytheoutputspecifications,orpostconditions,oftheroutines.Theabstractviewhidesthedatastructure,butprovideswindowsintoitthroughthespecifiedaccessingoperations.WordsandExpressionsconsiderablyadv.相当地；非常地subsume[səb'sju:m]vt.把……归入；把……包括在内abstractdatatype[计]抽象数据类型comprehensive[,kɔmpri'hensiv]adj.广泛的；综合的representative[,repri'zentətiv]a.代表性的succinctlyadv.简洁地；简便地propertiesn.性能；道具，内容（property的复数