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1、PassageoneHumanshaveusedthewindmilltoharnesswindpowerforthousandsofyears.However,itwasnotuntilthe19thcenturythatwindmillspossessedthefeaturesthatmadethemefficientinthesamewayasmodernwindturbineblades.Thewindmillwasrefinedwhenitsheavy,inefficientwoodenbladeswerereplacedwith
2、lighter,fastersteelbladesaround1870.Overthenextcentury,morethansixmillionsmallwindmillswerebuiltinthewesternUS,wheretheypumpedgroundwaterforlivestockandprovidedthedomesticwatersupplyforfamilieslivingonremoteranches.Thefirstlargewindmilltoproduceelectricitywasamulti-bladede
3、signwitha12-kilowattcapability,builtin1888.Today,windpowerisapromising,clean,safe,andenvironmentallyfriendlyenergyresourcethatcanserveasanalternativetoelectricitygeneratedbyfossilfuelssuchascoal,oil,andnaturalgas.In1999,wind-generatedelectricityexceeded10,000megawattsgloba
4、lly,whichamountstoapproximately16millionkilowatt-hoursofelectricity.Thisismorethanenoughtoservefivemedium-sizedcitieswithapopulationof350,000each.Wind-generatedelectricityisprojectedtobeoneofthedevelopingworld’smostimportantsourcesofenergy,anditalsohaspotentialforindustria
5、lizednations.Windpowercouldprovide20percentoftheelectricityintheUS,withturbinesinstalledonlessthanonepercentofthenation’slandarea.Withinthatarea,lessthan5percentofthelandwouldbeoccupiedbywindequipment;theremaining95percentcouldcontinuetobeusedforfarmingorranching.Passagetw
6、oProfessorsarenormallyfoundinuniversityclassrooms,offices,andlibrariesdoingresearchandlecturingtotheirstudents.Moreandmore,however,theyalsoappearasguestsontelevisionnewsprograms,givingexpertcommentaryonthelatesteventsintheworld.Thesetelevisionappearancesareofgreatbenefitto
7、theprofessorsthemselvesaswellastotheiruniversitiesandthegeneralpublic.Professorsbenefitfromappearingontelevisionbecausebydoingsotheyacquirereputationsasauthoritiesintheiracademicfieldsamongamuchwideraudiencethantheyhaveoncampus.Ifaprofessorpublishesviewsinanacademicjournal
8、,onlyotherscholarswilllearnaboutandappreciatethoseviews.ButwhenaprofessorappearsonTV,thou
