大学英语四级模拟试题(9)VIP免费

大学英语四级模拟试题(9)Directions:Therearefourreadingpassagesinthispart.Eachpassageisfollowedbysomequestions.ForeachquestiontherearefoursuggestedanswersmarkedA,B,CandD.YoushouldchoosetheonebestanswerandblackenthecorrespondingletterontheANSWERSHEETwithapencil.Passage1Howdoyousendamessagetoasubmergedsubmarine,particularlyonecarryingmiWatermaynotlooklikeabarriertocommunications,butappearancesaredeceiving.Waterstronglyabsorbsallelectromagneticwavesexceptbluegreenlightandextremelylowfrequencyradiowaves.Theverylowfrequencywavesnowusedtocontractsubmarinespenetratesonlyashortdistanceintotheocean,sothecraftmusteithersurfaceorsendupandantenna(天线)toreceivemessages,therebyincreasingitsweakness.Alasersystem---accurateoverlongdistancesandcapableofcarryingmoredatathantheverylowfrequencywaves---wouldtalktosubmarineattheirnormaldepths.Inthesystem,averybroadbeamspreadingoutfreelyinalldirectionswouldbescanned(扫描)overthousandsofsquaremilesofoceansothatitwouldn'tendangerboats,birdsorfish——orthesubmarinesitissupposedtoreach.Sinceonlyasmallfractionofthelasersystemwillmakeitswaythroughtheairandocean,receiversmountedonthesubmarinesmustbeablenotonlytodetectthelaserbutalsotodiscriminatebetweenitandsunlight.So,militaryscientistsarenowworkinghardonspecialfilterthatallowthroughonlytheprecisewavelengthsemittedbythelaser.Thefilteredlight,whentransformedintoelectricalsignal,canthenbedecoded.Militaryplannersareconfidentthatlasercommunicationwithsubmarinesisfeasible.1.Whichofthefollowingdoesthepassagemainlydiscuss?A.Missilescarriedbysubmergedsubmarines.B.Messagessentbysubmergedsubmarines.C.Blue-greenlasersusedbysubmergedsubmarines.D.Thewaytosendamessagetosubmergedsubmarines.2.WhichofthefollowingisTRUEaccordingtothepassage?A.Waterisabarriertoradiocommunication.B.Lasershavefoundwideapplicationinsubmarinecommunication.C.Waterabsorbsallkindsofelectromagneticwaves.D.Verylowfrequencyradiowavescannotbeusedtocontactsubmarines.3.WhichofthefollowingisNOTtrueofalasersystem?A.Itisabletomakeitswaythroughwater.B.Itisabletocommunicatewithsubmarinesatwork.C.Itsbeamreachesasubmergedsubmarinewiththehelpofanantenna.D.Itisabletocarrymoredatathanlowfrequencywaves.4.Thereferenceword“it”(Sentence1,para.3)refersto.A.theairB.thelaserbeamC.theoceanD.thesubmarine5.Whowouldbeverymuchinterestedinthepassage?A.MissilebuildersB.MilitaryscientistsC.FishermenD.ShipbuilderPassage2TheWestbeguntotakemorenoticeoftheEast.Thefifthvolumeofanenormousworkre-assessingtheChinesecontributiontoscienceandtechnologyistobepublishednextyear.Thefirstvolume,whichwaspublishedtwentyyearsago,setthetoneforthewholework.Init,evidencewasgiventoshowthatmanyinventionswhich,untilthen,westernhistorianshadclaimedforEurope,weremadefirstinChina.Theattempttorewritetheintellectualhistoryoftheworldwasnotreceivedwithoutprotestbysomereputablehistorians.However,theevidencethathasbeenpresentedsofarinthefirstfourvolumeshaspersuadedmanyhistorianswhowereskepticalatfirst.China'sinventionofpaper,printing,themagneticcompassandgunpowderhasneverbeendisputed,butthisnewhistoryhasaddedadvancedbridgedesign,mechanicalclocks,paddleboatsandmanyotherinventionstothelist.InthefourvolumespublishedsofarnoattempthasbeenmadetoexplainwhyChinahasnotkeptupwiththeWestinscienceandtechnologyinmoderntimes.ItisprobablethattheansweristobefoundinthesocialandeconomichistoryofChina,whereastaticsocietyu...