英语高考阅读理解练习和答案.doc

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1、45高考英语阅读理解专项练习（及答案）（一）Itisnotalwayseasytounderstandinventionsandnewdevelopmentsinscience.Tounderstandfiberoptics（光纤）,however,youcantryanexperiment.Putadroportwoofmileintotheglassofwater.Turnoffthelights.Shinethelightfromyourflashlight（手电筒）throughthetopoftheglassatanangle（角度）ofabout45de

2、grees.Putapieceofwhitepaperagainsttheglasswhenthebeam（光束）oflightisshining.Movethepapersoyoucanseewherethebeamiscomingoutoftheglass.Youshouldseeaspotoflight.Someofthelighthaspassedthroughthewaterandthroughtheglass.Youseeitonthepaper.Youalsoseeanotherbeamgoingdownintotheglass.Itisbeingre

3、flecteddownintotheglass.Nextmovetheflashlightsothatthebeamiscomingstraighterdown(30degrees)intothewater.Youwillseethesamephenomenon:someofthelightisreflectedbackintotheglass.Andsomeescapesout.Nowmovethebeamoflightfromtheflashlightslowlyupuntilyoucannotseeanylightescaping.Thispointiscal

4、ledthe“pointoftotalinternalreflection.”Thewordinternalmeans“inside.”Allthelightisstayinginsidetheglass.Thereisnobeamshowingabrightspotonthewhitepaper.Allthelightenergyisinsidetheglass.Theglassofmilkywaterislikeastrand（线）ofglass.Afiberoptictubeisabundleoflongthinstrandsofglass,reallyman

5、ytubes.However,theprinciple（原理）isthesame:atacertainangle,allthelightenergythatgoesintotheglassfibercomesouttheotherend.Lightisenergy.Soundisenergy.Radiowavesandelectricityarebothenergy.Theycanallbechangedintolight,andaslighttheycanalltravelalongaglassfiber.Lighttravelsattherateof186,00

6、0milespersecond.Therefore,amessagecantravelthatfastinaglassfiber.Thisistheprinciple,orlawofnature,thatmakesfiberopticswork.1．Whichfigureshowsthelaststepoftheexperiment?2．Thepurposeoftheexperimentistotellus.A．howfastlighttravelsB．howfiberopticsworksC．howlighttravelsinaglassofwaterD．howf

7、iberopticshelpsmankind3．Intheexperiment,makesthebiggestdifference.A．theangelatwhichtoshinethelightfromtheflashlightB．theamountofwaterintheglassofmilkC．thenumberofdropsofmilktopourintotheglassofwaterD．thesizeoftheholethroughwhichtoshinelightfromtheflashlight4．Thelaststepistoprove.A．no