机电英语（高等职业）全套教学课件

机电英语Unit1全套可编辑PPT课件Unit1SectionⅠSpeakingandListeningSectionⅡReadingPassage1KindsofSteePassage2TheHistoryofElectricityPassage3OpticalCommunicationSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit2SectionⅠSpeakingandListeningSectionⅡReadingPassage1MachineElementsPassage2ElectronicComponentsPassage3NewNetworkTechnologySectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit3SectionⅠSpeakingandListeningSectionⅡReadingPassage1TypesofBearingsPassage2HowDoesaWashingMachineWorkPassage3ComponentTestingSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit4SectionⅠSpeakingandListeningSectionⅡReadingPassage1LathePassage2CircuitsPassage3EvolutionofNetworkSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit5SectionⅠSpeakingandListeningSectionⅡReadingPassage1MachinesUsingNCPassage2RefrigeratorsPassage3PulseDigitalCircuitSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit6SectionⅠSpeakingandListeningSectionⅡReadingPassage1DimensionandTolerancePassage2TransformerPassage3CommunicationsandCommunicationSystemSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit7SectionⅠSpeakingandListeningSectionⅡReadingPassage1Computer-aidedDesign(CAD)Passage2HowDoesaLiquidCrystalDisplayTVWorkPassage3IntroductionofGPSSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeUnit8SectionⅠSpeakingandListeningSectionⅡReadingPassage1MachiningCentersPassage2IndustrialRobotsPassage3IntroductiontoDigitalSignalProcessingSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeContentsSectionⅠSpeakingandListeningSectionⅡReadingSectionⅢTranslationSectionⅣWritingSectionⅤLanguageSkillDevelopmentSectionⅥFunTimeSectionⅠSpeakingandListeningSectionⅠSpeakingandListeningSpeaking

欧美电影的受众不是“英语学习者”，而是面向以英文为母语的国际市场。因此我们听到的电影台词基本是比较“真实”的，比较接近现实生活，包括用法习惯、语气语调语速等方面。电影里的用语往往比书本里的更本土、更地道。譬如现在欧美人之间互相打招呼很少说“Howdoyoudo?”，而是一般会说“Howareyoudoing?”“How'sitgoing?”“What'sup?”等。回复一般也不会是“Fine，thankyou,andyou?”而是“Prettywell.”“Good.”“Nottoobad.”“Sameasusual.”之类的。有时候书本在语言学习上不如电影灵活，甚至很多东西在英文课或辅导班上也很难学习到，譬如俚语、本土用语习惯、讲话方式等。举个例子，打出租车到目的地了，怎么说？“Stophere,please.”虽然也可以这么说，但是其实听上去很不地道，也不是很礼貌，不妨说“Canyoudropmeoffhere?”之类。或者一些小习惯，比如在英国听到别人打喷嚏一般会跟对方说一句“Blessyou.”，在讲到一个不怎么好的事情的时候会“touchwood”以防不幸言中。如果没有那么多机会去欧美国家身临其境地体会地道的英语表达，看电影学习英语，尤其是在口语方面，是一个很好的途径。看电影学英语应该注意以下几个方面。SectionⅠSpeakingandListeningSpeaking选电影看字幕反复听记笔记SectionⅠSpeakingandListeningExercisesDirections:Readtheclassicfilmclipandtrytorecitethem.01Amancanbedestroyedbutnotdefeated. —TheOldManandtheSea一个人可以被毁灭，却不能被打败。 ——《老人与海》02I'monlybravewhenIhavetobe.Beingbravedoesn'tmeanyougolookingfortrouble.—TheLionKing我只是在必要的时候才会勇敢，勇敢并不代表你要到处闯祸。 ——《狮子王》SectionⅠSpeakingandListeningIttakesastrongmantosavehimself,andagreatmantosaveanother.—TheShawshankRedemption坚强的人只能救赎自己，伟大的人才能拯救他人。——《肖申克的救赎》I'monlybravewhenIhavetobe.Beingbravedoesn'tmeanyougolookingfortrouble.—TheLionKing我只是在必要的时候才会勇敢，勇敢并不代表你要到处闯祸。 ——《狮子王》030405IfigurelifeisagiftandIdon'tintendonwastingit.Youneverknowwhathandyou'regoingtogetdealtnext.Youlearntotakelifeasitcomesatyou. —Titanic我觉得生命是一份礼物，我不想浪费它，你不会知道下一手牌会是什么，要学会接受生活。 ——《泰坦尼克号》 SectionⅠSpeakingandListeningListeningPRETCO听力理解题型在日常交际中，听力一直占十分重要的地位，人们无论是看电影、电视，听广播、演讲、报告，相互之间进行交谈，都离不开听力，“听”是用语言交际所必须掌握的一项最基本的技能。因此，在国内外的英语教学和各种英语考试当中，无不把听力作为一项重要内容。听力考试的主要目的是考核学生通过耳朵获取有声信息的能力，听力理解能力的强弱不仅取决于听音者能否熟练地掌握必要的词汇和语法知识，以及在听的过程中能否敏锐地辨析语音的变化和语调的含义，也涉及听音者对所听内容背景知识的了解，以及结合所获取的信息进行加工处理的能力。多年的实践表明，听力的提高是比较困难的，也历来是中国学生学习外语的薄弱环节。因此，有针对性地进行适当的训练，对提高听音者的听力理解能力不无好处。英语考试中听力成绩的提高，不仅取决于基础语言技能的掌握，而且涉及熟悉题型，掌握技巧。目前，面向高职、高专层次的高等学校英语应用能力考试（PracticalEnglishTestforColleges，以下简称PRETCO）的听力理解部分已被采用或可能被采用的主要题型有以下几种：①简短对话（Shortdialogue）；②会话（Conversation）；③短文理解（Shortpassage）；④听写填空（Spotdictation）。SectionⅠSpeakingandListeningListening

PRETCO的听力理解部分考查学生对所听对话、会话和简单短文的理解能力。听力材料的语速为每分钟100词左右，词汇或短语不超过《高职、高专英语课程教学基本要求》所规定的范围。SectionⅠSpeakingandListeningExercisesDirections:Thispartistotestyourlisteningability.Itconsistsof3sections.SectionA

Directions:Thissectionistotestyourabilitytogiveproperanswerstoquestions.Thereare5recordedquestionsinit.Aftereachquestion,thereisapause.Thequestionswillbespokentwotimes.Whenyouhearaquestion,youshoulddecideonthecorrectanswerfromthe4choicesmarkedA,B,CandD.

Example:

Youwillhear:Youwillread:A.I'mnotsure. B.Youareright.C.Yes,certainly. D.That'sinteresting.Fromthequestion,welearnthatthespeakerisaskingthelistenertoleaveamessage.Therefore,“C.Yes,certainly.”isthecorrectanswer.A.Busesaretoofew.B.Peopleliketoridebicyclesmorethantakebuses.C.Morebicyclesthanbusesareseeninthiscity.D.Therearemorebusesandbicyclesinthiscitythancars.SectionⅠSpeakingandListening0302040501A.Iworkinafactory. B.Ireadnewspaper.C.Ihaveboughtsomethingforyou. D.Iamverybusynow.A.Frankisafastrunner.B.NobodyrunsfasterthanFrank.C.Frankisoneofthefastestrunners.D.Frankrunsasfastasalltheothers.A.IdidEnglishassignmentsonly.B.Ididmathsassignmentsquickly.C.Ifailedtodomathsassignments.D.IfoundEnglishassignmentseasier.A.Sayinganddoingarethesame.B.Doingismoredifficultthansaying.C.Sayingmaybemoredifficultthandoing.D.Doingandsayingaredifferent.SectionⅠSpeakingandListeningExercises

Directions:Thissectionistotestyourabilitytounderstandshortdialogues.Thereare5recordeddialoguesinit.Aftereachdialogue,thereisarecordedquestion.Boththedialoguesandquestionswillbespokentwotimes.Whenyouhearaquestion,youshoulddecideonthecorrectanswerfromthe4choicesmarkedA,B,CandD.

SectionBA.Tookpianolessons.B.Didn'tlikethepiano.C.Boughtapiano.D.Dislikedhispianoteacher.A.Asecretary. B.Hisboss.C.Thebusinessofficer. D.Theoperator.SectionⅠSpeakingandListening0102050403A.Theyarewatchingtelevision.B.Theyarelisteningtoradio.C.Theyareswimminginthechannel.D.Theyarechangingtheirnewsprograms.A.20dollars. B.15dollars.C.24dollars. D.21dollars.A.Hethinksit'sagoodidea.B.Hedoesn'tliketheidea.C.Hethinkshemightputforwardabettersuggestion.D.Heaskshertochangeforabetteridea.SectionⅠSpeakingandListeningExercisesSectionC

Directions:Inthissectionyouwillheararecordedshortpassage.Thepassageisprintedonthetestpaper,butwithsomewordsorphrasesmissing.Thepassagewillbereadthreetimes.

BecauseAmericaisahometosomanydifferent_______,onecanfindalmostanykindofrestaurantinalmostallthelargercities.Costsfora______isverygreatlyfromcheaptovery_______inrestaurantsoflargercities.AstheresultofAmerican'spassionfor______,fastfoodshopshavebecomewidespreadand______intheU.S.,suchasMcDonald'sandKentuckyFriedChicken.Therearealsodrive-infastfoodrestaurants.SectionⅡReadingSectionⅡReadingKindsofSteelTherearetwogeneralkindsofsteels:carbonsteelandalloysteel.Carbonsteelcontainsonlyironandcarbon,whilealloysteelcontainssomeother“alloyingelements”suchasnickel,chromium,manganese,molybdenum,tungsten,vanadium,&etc.钢分两大类：碳钢与合金钢。碳钢只含有铁和碳，而合金钢则含有某些其他“合金元素”，比如镍、铬、锰、钼、钨、钒等。钢的种类Passage1SectionⅡReading1.Carbonsteels(1)Lowcarbonsteelcontainingfrom0.05to0.15percentcarbon.Thissteelisalsoknownasmachinesteel.(2)Mediumcarbonsteelcontainingfrom0.15to0.60percentcarbon.(3)Highcarbonsteelcontainingfrom0.6to1.50percentcarbon.Thissteelissometimescalled“toolsteel”.2.Alloysteels(1)Specialalloysteel,suchasnickel,chromiumsteel.1．碳钢低碳钢（含碳量＝0.05%～0.15%），这种钢还称为“结构钢”。中碳钢（含碳量＝0.15%～0.60%）。高碳钢（含碳量＝0.60%～1.50%），这种钢也称为“工具钢”。2．合金钢（1）特种合金钢，如镍钢、铬钢。SectionⅡReading(2)High-speedsteelalsoknownasself-hardeningsteel.Thepropertiesofcarbonsteelsdependonlyonthepercentageofcarbontheycontain.Lowcarbonsteelsareverysoftandcanbeusedforboltsandformachinepartsthatdonotneedstrength.Mediumcarbonsteelisabettergradeandstrongerthanlowcarbonsteel.Itisalsomoredifficulttocutthanlowcarbonsteel.（2）高速钢，还叫作自硬钢。碳钢的性能主要取决于钢中的含碳量。低碳钢质软，故用于制造没有强度要求的螺栓和机器零件。中碳钢是较高级钢，强度比低碳钢高，切削加工也较低碳钢困难。SectionⅡReadingHeatingittoacertaintemperatureandthenquicklycoolinginwatermayhardenhighcarbonsteel.Themorecarbonthesteelcontainsandthequickerthecoolingis,theharderitbecomes.Becauseofitshighstrengthandhardness,thisgradeofsteelmaybeusedfortoolsandworkingpartsofmachines.Butforsomespecialuses,forexamples,forgears,bearings,springs,shaftsandwire,carbonsteelscannotbealwaysusedbecausetheyhaveonpropertiesneededfortheseparts.高碳钢可借助加热到一定温度，然后通过在水中快速冷却的方法使之硬化。钢的含碳量越高，冷速越快，钢就变得越硬。这种钢，因为其强度、硬度高，可用于生产刀具和机器的工作零件。但对于某些特殊用途的零件来说，比如齿轮、轴承、弹簧、轴，以及金属丝等，因为碳钢不具备这些零件所需要的性能，所以常常不以采用。SectionⅡReadingSomespecialalloysteelsshouldbeusedforsuchpartsbecausethealloyingelementsmakethemtougher,stronger,orharderthancarbonsteels.Somealloyingelementscausesteeltoresistcorrosion,andsuchsteelsarecalledstainlesssteels.Heat-resistantsteelismadebyaddingsometungstenandmolybdenum,whilemanganeseincreasesthewearresistanceofsteel.Vanadiumsteelsresistcorrosionandcanstandshocksandvibration.对这类零件可采用某些特殊的合金钢，这是因为合金元素能提高钢的任性、强度、硬度。有些合金元素能使钢耐腐蚀，所以这种钢称作不锈钢。耐热钢即通过加入钨和钼而制得，而锰能增加钢的耐磨性能。钒钢能够抗腐蚀并能承受冲击和振动。SectionⅡReadingToolsmadeofhigh-speedsteelcontainingtungsten,chromium,vanadium,andcarbon,maydotheworkatmuchhigherspeedsthancarbontoolsteels.用含有钨、铬、钒、碳的高速钢制作的刀具能够比碳素工具钢以高得多的速度进行切削加工。carbon ['kɑːb(ə)n] n.碳nickel ['nɪk(ə)l] n.镍chromium ['krəʊmɪəm] n.铬manganese ['mæŋgəniːz] n.锰molybdenum [mə'lɪbdənəm] n.钼tungsten ['tʌŋst(ə)n] n.钨vanadium [və'neɪdɪəm] n.钒harden ['hɑːd(ə)n] v.硬化；淬火bolt [bəʊlt] n.螺栓gear [gɪə] n.齿轮bearing ['beərɪŋ] n.轴承SectionⅡReadingNewWords&Phrasesshaft [ʃɑːft] n.轴corrosion [kə'rəʊʒ(ə)n] n.腐蚀stainless ['steɪnlɪs] adj.不锈的alloy ['ælɒɪ] n.合金vt.把……铸成合金medium ['miːdɪəm] n.中间物，介质

adj.中间的，中等的，半生熟的fine [faɪn] adj.细，纤细，纯粹；（金银等）纯净的；精炼的；含量高的vibration [vaɪ'breɪʃ(ə)n] n.振动，颤动heat-resistant ['hiːtri,zistənt] adj.耐热的，抗热的 SectionⅡReadingNewWords&Phrasestoolsteel

工具钢heat-resistantsteel 耐热钢self-hardeningsteel

自硬钢high-speed

高速的high-speedsteel 高速钢SectionⅡReadingNewWords&PhrasesSectionⅡReadingExercises

Answerthefollowingquestions.01Whatiscalled“carbonsteel”?Whatabout“alloysteel”?02Whatmethodsareavailableforimprovingthehardnessofhighcarbonsteel?SectionⅡReadingWhatarethemachinepartsthatdonotneedstrengthmadeof?Whydothealloyingelementssuchaschromiumandtungstenincreasethehardnessandstrengthofsteel?030405Whatisheat-resistantsteel?Whataboutstainlesssteels?SectionⅡReadingPlacea“T”(true)oran“F”(false)besidethefollowingsentencesaccordingtothetext.High-speedsteelissometimescalledself-hardeningsteel.1Alloyshavingmorethan0.6%carbonarecalledhighcarbonsteels.2Alloyscontaining0.15%(orless)carbonarecalledlowcarbonsteels.3SectionⅡReadingSteelscontainmorecarbonthancastirons.4Lowcarbonsteelisharderthanhighcarbonsteel.5Thepropertiesofcarbonsteelsdependnotonlyonthepercentageofcarbontheycontain,butalsoonthealloyingelements.6ToolsmadeofHigh-Speedsteeldotheworkatmuchlowerspeedsthancarbonsteels.7Stainlesssteelscontainsomealloyingelements,whichcausesteelstoresistcorrosion.8SectionⅡReadingFillintheblankswiththeproperwordsgiveninthebrackets,changingtheformifnecessary.High-speedsteelisalso___________________(know)asself-hardeningsteel.01Themorecarbonthesteelcontainsandthe________________(quick)coolingis,the__________________(hard)itbecomes.02Highcarbonsteelmaybe____________________(harden)byheatingittoacertaintemperatureandthenquicklycoolinginwater.03Heat-resistantsteelismadeby_______________(add)sometungstenandmolybdenum.04SectionⅡReadingCarbonsteelcontainsonlyironandcarbon,whilealloysteelcontainssomeother“alloyingelements”.Specialalloysteel,suchasnickel,chromiumsteel.02Highcarbonsteelcontainingfrom0.6to1.50percentcarbon,thissteelisalsonamed“toolsteel”.03Toolsmadeofhigh-speedsteelcontainingtungsten,chromium,vanadium,andcarbon,maydotheworkatmuchhigherspeedsthancarbontoolsteels.TranslatethefollowingsentencesintoChinese.0104SectionⅡReadingTheHistoryofElectricityAsearlyasthelatterpartof16thcentury,experimenterswereexploringthebehaviorofstaticelectricity.WillianGilbertexperimentedwithelectricchargesanddischarges.In1750,BenjaminFranklinprovedthatlightningwaselectricalinnature.Neitherinvestigator,discoveredanythingthatwassignificantfromthestandpointofelectricity.Discoveryofthepresenceofmagnetismincertainrocksprecededtheearliestknowledgeofelectricity.早在16世纪后期，人们就开始探索静电。威廉·吉尔伯特对充电和放电开始了研究。1750年，本杰明·富兰克林证明了雷电属于自然现象。但在那个年代，研究人员还没有发现任何立足于电流应用方面的重要线索。电学发展史Passage2SectionⅡReadingDiscoveryofthepresenceofmagnetismincertainrocksprecededtheearliestknowledgeofelectricity.Suchknowledgewascommonabout600B.C.Applicationsofelectricalknowledgewerecompletelyabsentinthisera.In1800AlessandroVoltadiscoveredtheprincipleoftheelectricbattery.Thevoltaiccellwasoneofthemostimportantdiscoveriesinthehistoryoftheelectricalart,becauseitprovidedacontinuoussourceofappreciableamountsofelectricpoweratreasonablelowvoltage.Itwasanessentialcomponentoftheearlycommunicationsystems,suchasthetelephoneandtelegraph.发现某些岩石中存在磁场推动了电知识的产生。在公元前600年左右，电气知识的应用几乎为零。在1800年，亚历山德罗·伏特发现了电池原理。伏特电池是电子技术发展史上最重要的发现之一，因为它能够在适度的低压条件下提供可观的持续电流。它是早期通信系统（如电话、电报）的必要组成部分。SectionⅡReadingThefirstUnitedStates'patentontheelectricaltelegraphwasobtainedbyJohnGroatin1800.TheinventionofapracticalelectromagnetwasannouncedbyJosephHenryin1827.TheseinventionsbyGroatandHenryopenedthewayforastillmoresignificantinvention,theelectromagnetictelegraph.Theprincipleofthisforerunnerofthecommunicationsindustrywasconceivedin1831,provenpracticalin1837,andpatentedin1840bySamuelFinleyBreese.Morse.FewdevelopmentshavehadgreaterimpactonAmericanlifethanMorse'sinvention.Hisideapavedthewayforthefirstsystemofelectricalcommunication,thisinturnledtothetelephoneandlatertothewirelesstelegraph.在1800年，约翰·格鲁特获得了美国第一个电报专利。在1827年，约瑟夫·亨利将电磁应用的发明公布于世。这两项发明为电学方面更多重要的发明开辟了道路，比如说电磁电报。由于这些理论的发明，在1831年形成了通信业，并于1837年获得了实践性的证明，1840年，萨慕尔·摩斯获得了此项专利。在那时几乎没有任何进步能像摩斯的发明那样给美国民众带来如此大的影响。他的发明为第一个电子通信系统的建立铺好了道路，从而促使了后来的电话和无线电报的发明。SectionⅡReadingThediscoveryofelectromagneticinductionbyMichaelFaradayin1831establishedmanyprinciplesformodernmachines.OneofthefirstimportantdevelopmentsbasedonthedisclosuresofFaradaywastheDCgenerator.Motors'generators,transformersandmanyotherelectricaldevicesfoundinheavyelectricalindustryweremadepossiblebythediscoveriesofFaraday.ThecontributionsofFaradayintheelectricalpowerindustryandcomparabletothoseofMorseinthefieldofcommunications.

1831年，迈克尔·法拉第电磁感应定律的发现为现代机器的发明提供了理论基础。

法拉第电磁感应定律的重要作用之一就是直流发电机。它使得重型电气工业中的发动机、发电机、变压器和许多其他电器装置的发明成为可能。法拉第对电力工业的贡献可以媲美于摩斯在通信业的贡献。SectionⅡReadingWiththedevelopmentofthehigh-resistancecarbonfilamentlampbyThomasEdisonin1880,theDCgeneratorbecameoneoftheessentialcomponentsoftheconstant-potentiallightingsystem.Commerciallightingandresidentiallightingbecamepracticalandtheelectriclightandpowerindustrywereborn.Oneofthemostcommonusesfordirectcurrentduringthisperiodwasforstreetlighting.Thefirsttransformerwasannouncedin1883.Thisdeviceprobablydidmoretorevolutionizethatthehigh-voltagelow-currentsystemsoverthelow-voltagehigh-currentsystemsofpowertransmissionwerewell-known.在1880年，随着托马斯·爱迪生的高电阻碳丝电灯的发明，直流电动机就变成了连续照明系统中必要组成部分。商业照明和住宅照明得以实现，电照明和电力工业诞生了。在这一时期，直流电主要用于街道照明。在1883年，第一台变压器产生了，变压器给电能的传输带来了前所未有的革命。众所周知，在电力传输的过程中，高电压小电流要优于低电压大电流。SectionⅡReadingFollowingthediscoveryofthetransformedtohighervoltagesfortransmissionovergreatdistances(severalhundredmiles),andthenreducebytransformerstolowervaluesforutilization.In1888NikolaTeslawasgrantedapatentonthepolyphaseACinductionmotor,whichsoonbecamethemostcommonlyusedmotorforsupplyinglargeamountsofpowerinitsimprovedstate.Itismostextensivelyusedtoday.In1876AlexanderGrahamBellinventedthetelephone.Thisdevicewassoonputintouseand,asaresult,anotherhugeindustrywasestablished.随着变压器的发明，电能可以由低电压转换为高压进行远距离传输从而减少能耗。在1880年，随着托马斯·爱迪生的高电阻碳丝电灯的发明，直流电动机就变成了连续照明系统中必要组成部分。商业照明和住宅照明得以实现，电照明和电力工业诞生了。在这一时期，直流电主要用于街道照明。在1883年，第一台变压器产生了，变压器给电能的传输带来了前所未有的革命。众所周知，在电力传输的过程中，高电压小电流要优于低电压大电流。随着变压器的发明，电能可以由低电压转换为高压进行远距离传输从而减少能耗。static ['stætɪk] adj.静电的；静止的；静态的standpoint ['stæn(d)pɒɪnt] n.立足点magnetism ['mægnɪtɪz(ə)m] n.磁场，磁力voltaic [vɒl'teɪɪk] adj.伏打的patent ['pæt(ə)nt;'peɪt(ə)nt] n.专利electromagnetic [ɪ,lektrə(ʊ)mæg'netɪk] n.电磁铁；电磁体filament ['fɪləm(ə)nt] n.灯丝polyphase ['pɒlɪfeɪz] adj.多相的SectionⅡReadingNewWords&PhrasesSectionⅡReadingExercisesChoosetherightstatementsaccordingtothepassage.In1750BenjaminFranklinprovedthatlightningwaselectricalinnature.AIn1888N.TeslawasgrantedapatentonthepolyphaseACinductionmotor.DThefirstUnitedStates'patentontheelectricaltelegraphwasobtainedbyJ.Groatin1800.BIn1800Morsediscoveredtheprincipleoftheelectricbattery.CSectionⅡReadingAnswerthefollowingquestions.0102Whodiscoveredtheprincipleoftheelectricbatteryin1800?Whatwasthediscoverythatestablishedmanyprinciplesformodernmachines?SectionⅡReadingMatchtheitemslistedinthefollowingtwocolumns.voltage transmissioncommunication charge DCgenerators01OPTION02OPTION03OPTION04OPTION05OPTION电荷传输通信电压直流发电机AOPTIONBOPTIONCOPTIONDOPTIONEOPTIONSectionⅡReadingOneofthemostcommonusesfordirectcurrentduring__________（这一时期）wasforstreetlighting.CompletefollowingsentencesbytranslatingtheChineseinthebracketsintoEnglish.121Theadvantagesofhigh-voltagelow-currentsystemsoverthelow-voltagehigh-currentsystemsofpowertransmissionwere_________（众所周知）.Fewdevelopmentshavehad___________（巨大影响）onAmericanlifethanMorse’sinvention.SectionⅡReadingOpticalCommunicationImportantstepshavebeentakensince1974towardfindingmajorapplicationsforopticalfibersincommunications.Withthedevelopmentofspacesystemsandtechnology,theuseofradioopticsforcommunicationthroughtheatmosphereandinspacewillcontinuetogrowinimportance.Buttheprospectofdevelopinglight-wavecommunicationssystemstocompetewithandexpandtraditionalcommunicationsserviceshaveshiftedtheemphasistowardtheuseoflight-wave-guidingfibers.从1974年发现光纤在通信中的重要应用以来，人们相继取得了多个重大进展。随着空间系统和技术的发展，通过大气和空间进行无线光学通信将是持续发展的重点。但是光波通信系统与传统通信服务系统之间的竞争和扩展的重点已经转到利用光导纤维上。光纤通信Passage3SectionⅡReadingExperimentaloptical-fibertransmissionsystemsarealreadyinuseinsomeofthetelephonesystemsinafewcountries.Thesuccessofindustryinturningsucheffectivetechniquestoadvantagebydevelopinglow-costproductswilldeterminetheimpactwhichopticalfibershaveoncommunications.Thetelephonesystemcanbedividedintothreenetworks:thelocalnetwork,whichtiescustomerstotheirrespectivelocalswitchingofficersalmostonaone-to-onebasis;large,relativelyshortgroupsoflinetietheswitchingofficestogether;andevenlargerandmuchlongergroupsoflinesinterconnectcities.实验性的光纤传输系统已经在几个国家的电话系统中使用。借助发展低成本产品，把实用技术转变成可获利的工业生产将决定光纤在通信中的应用前景。电话系统可以分为三个网络。当地网，连接客户与当地的中继局；中继网，连接各中继局；城市之间的远程网。本地线路，通常称环路，连接用户与中继局，大都建立在一对一基础上；大的，短组线路把各中继局连接在一起；更大、更长的组线实现城市互联。SectionⅡReadingEventhoughopticalfibersaremuchsmallerthanwirepairs,andsilica(themostwidelyusedmaterialinfibers)isvastlymoreabundantthancopper,thecostofpreparingtherodsfromwhichopticalfibersaredrawnisseveraltimesgreaterthanthecostproducingwires.Moreover,studiessuggestthatthismaybethecaseforsometime.However,fibersystemscancarrysomanymoretelephoneconversationsatthesametimethanwirepairs,andcancarrythemsomuchfartherwithoutamplificationofregeneration,thatwhentherearemanytelephonecallstobecarriedbetweenpointssuchaswitchingoffices,fibersystemsareeconomicallyattractive.尽管光学纤维比金属线对要细，并且二氧化硅比铜丰富得多，但是制造光纤的代价却是生产通信的好几倍。而且研究者们认为这种情况还将持续一段时间。

然而，光纤系统同时可以容纳比金属线对多得多的电话线路，并且在不需要放大的情况下把信号送得更远。在两点之间，比如中继局有很多电话呼叫传送的时候，光纤系统就是特别经济的。SectionⅡReadingThustheinterofficetrunknetworkwillbethefirsttobenefitfromthisnewtechnology.Infact,varioustrunk-orientedcommunicationssystemsareunderconstructionorinoperationinmanyindustrializedcountries.Opticalfibersarealsobeingconsideredfortheinter-citynetwork,competitionismoredifficult,though,withexistinghigh-capacitysystemsthatusecoaxialtransmissionlines,wave-guidemicro-waveradio,ansatellite.Largerfiberbandwidth,lowerloss,anmorereliableopticalsourceswouldmakeopticalfibersmorecompetitiveinthissector.Asthesecharacteristicsareimproved,opticalfiberswillmostlikelybeusedforunderseacablesystemsaswell.因此，局间中继网是最先受益于这种新技术的。事实上，在许多工业化国家，各种与中继有关的通信系统正在建设或者已经运行。光学纤维也被用于城市互联网。虽然存在同轴传输线、波导微波无线电系统和卫星传输这些大容量系统，但是竞争仍然很激烈。宽频带、低损耗、可靠性高使得光学纤维更具有竞争力。随着这些特性被加以改善，光学纤维最有可能被用于海底光缆系统。SectionⅡReadingAlthoughitisdifficulttopredictthespecificdetails,itisnotunlikelythatsomedaylow-loss,large-bandwidthopticalfibersandtherequiredspecialelectronicsmaybehardlymoreexpensivethancopperwiresforprovidingalocalphoneservice.Atthattimeitisconceivablethataprivatelocaltwo-waytelevisionserviceusingthesamefibersmaybealmostasinexpensiveasatelephoneservice.Afewopticalfibersdatalinksystemsarealreadyonthemarket,andmoreareunderdevelopment.Intendedforcomputerandcomputerapplications,theyhavetheadvantageofsmallcablesizeandweightandimmunitytolightingandotherelectromagneticinterference.虽然预测一些具体的细节比较困难，但还说不定有一天低损耗、宽频带的光学纤维系统在应用于当地电话系统时并不比铜线昂贵。那时候，可以想象使用同一光纤的私人、当地两路电视服务系统将不再比一路电话系统贵。市场上已经有几条光纤数据连接系统，更多的还在发展中，在计算机和计算机应用方面，光纤已经在大小、重量、抗闪电和抗电磁干扰方面优于小型电缆。electromagnetic [ɪ,lektrə(ʊ)mæg'netɪk] adj.电磁的prospect ['prɒspekt] n.前景expend [ɪk'spend;ek-] vt.发展，扩展emphasize ['emfəsaɪz] vt.重点，强调fiber ['faibə] n.纤维impact ['ɪmpækt] vt.冲击，影响optics ['ɒptɪks] n.光学competition [ˌkɒmpəˈtɪʃn] n.竞争，对抗tie [taɪ] vt.连接respective [rɪ'spektɪv] adj.各自的SectionⅡReadingNewWords&Phrasestrunk [trʌŋk] n.中继loop [luːp] n.环，回路relative ['relətɪv] adj.有关系的silica ['sɪlɪkə] n.硅石，二氧化硅abundant [əˈbʌndənt] adj.丰富的，充裕的industrialized [ɪn'dʌstrɪəlaɪzd] adj.工业化的coaxial [kəʊ'æksɪəl] adj.同轴的cable ['keɪb(ə)l] n.电缆predict [prɪ'dɪkt] vt.预言，预测unlikely [ʌn'laɪklɪ] adj.未必的，不可能的SectionⅡReadingNewWords&Phrasesconceivable [kən'siːvəb(ə)l] adj.不可想象的immunity [ɪ'mjuːnɪtɪ] n.抗扰性interference [ɪntə'fɪər(ə)ns] n.干涉，干扰forsometime 暂时competewith 与……竞争turn…toadvantage 使……变为有利haveimpacton 对……有影响divideinto 分为benefitfrom 受益于opticalfiber 光学纤维light-wave-guidingfiber 光导纤维SectionⅡReadingNewWords&PhrasesSectionⅡReadingExercisesAnswerthefollowingquestions.Whenhavesomeimportantstepsbeentaken?Whatwilldeterminetheimpactwhichopticalfibershaveoncommunications？Howmanynetworkscanthetelephonesystembedividedinto?Whatarethey?Whenarefibersystemseconomicallyattractive?Whatwouldmakeop