lesson90课件
日期：2010-02-19 02:46
WelcometomyclassAnswerthefollowingquestions1Howwasonetelephoneconnectedwithanotherinthepast?2Howisonetelephoneconnectedwithanothertoday?BythickheavymetalwiresByverythinglasspipesandsatelliteelectricalsignalselectricalsignalsHowdoesatelephonework?Whataresatellitesusedfor?AmericaChinaelectricalsignalselectricalsignalsWhatwasthewaytosendsignalsinthepast?metalwireslightsignalslightsignalsHowtosendsignalsnow?thinglasspipestoonoisy!notclear!veryclearelectricalsignalselectricalsignals光纤管thewaysinwhichnewmodelsoftelephonecanbeused1conferencecalling2dialling3redirection4callwaiting(电话会议)(缩位拨号)(呼叫转移)(呼叫等待)conferencecallingABCDEcallwaitingABCABBcredirectionChoosethebestanswers1Whenyouspeakintothetelephone，thewavesofyourvoiceareturnedinto____AelectricalsoundsBelectricalsignalsClightsignals2Thehandleofanoldtelephonewasusedfor______AproducingenoughelectricitytomakeacallBconnectingwithanothertelephoneCg，
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