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The very north and south {{U}}regions{{/U}} are covered with ice and snow.
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Desertperennialslosetheirleavesaftertherainyseasonjustastreeslosetheirsinwetterclimatesbeforewinterarrivesbutthereasonsforthisfeaturearedifferent.
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{{*HTML*}}阅读下面的短文文章中有5处空白文章后有6组文字请根据文章的内容选择5组文字将其分别放回文章原有位置以恢复文章原貌 ??Thereareabout350speciesofsharks.Thelargestsharksare thewhalesharkandthebaskingsharkwhichfeedonplanktonandsmallfish. Theadultwhalesharkgrowstoabout13meterslongwhilethebaskingshark extendsalittleover8meters.{{U}}?46?{{/U}}Ontheotherhandthere areanumberofthemwhichhaveattackedandkilledswimmers.Thesesharks includethegreathammerheadbluewhitetipandofcoursethegreatwhite shark.??{{U}}?47?{{/U}}Thegreatwhitegrowstobetween 5and8meterslongandcanweighmorethan1300kilograms.Itcanswimthrough theeateratspeedsreaching32kilometersperhour.Howeveroneofthefastest swimmersinthesharkfamilyisthebluesharkwhichcanswimataspeedof nearly752kilometersperhour.??{{U}}?48?{{/U}}They cangrowaslongas5centimetersandtheyareverysharp.Unlikehumanswho havetwosetsofteethintheirlifetimesomesharkscanhaveasmanyas5or 6sets.Itisrareforasharktohavefewerthan4sets.Itisrareforashark tohavefewerthan4sets.Astheshark’steetharewornouttheyfalloutand arereplacedbythenextrow.??{{U}}?49?{{/U}}Ina lifetimesomesharkscangrowandlosebetween10000and30000 teeth.??Seabiologistshavediscoveredthatthesharkhasa remarkablylargebrainandawell-developedsensorysystem.Theanimalhasan extraordinarysenseofsmellandexcellentvision.??{{U}} ?50?{{/U}}Specialsensorypitsontheshark’snoseandchincan detectweakelectricalfieldsinthewaterthatareproducedbyfishandother animals.Scientistshaveconcludedthatsharksassociatefoodwithelectrical fields.Scientistsalsobelievethatsharkscreatetheirownelectricalfields toaimtheminknowingwheretogointhesea.???A.Mustof thespeciesarenotparticularlycruel.???B.Sharkshave livedonearthformorethan180millionyears.???C.The greatwhiteisthelargestandcruelestofallanimalsknowntoattack humans.???D.Somesharkscanwearoutafullsetofteeth inlessthan6months.???E.Oneofthemostunusualaspects ofthesharkisitsteeth.???F.Butsharksarealso sensitivetoelectricalfields.
{{*HTML*}}{{B}}第三篇{{/B}} ??Volcanicfireandglacialiceare naturalenemies.Eruptionsatglaciatedvolcanoestypicallydestroyicefields astheydidin1980when70percentofMountSaintHelensicecoverwasde molished.Duringlongdormantintervalsglaciersgaintheupperhandcutting deeplyintovolcanicconesandeventuallyreducingthemtorubble.Onlyrarely dothesecompetingforcesofheatandcoldoperateinperfectbalancetocreate phenomenonsuchasthesteamcavesatMountRainierPark.? ?LocatedinsideRainier’stwoice-filledsummitcratersthesecavesforma labyrinthoftunnelsandvaultedchambersaboutoneandone-halfmilesintotal length.Theircreationdependsonanunusualcombinationoffactorsthatnature almostneverbringstogetherinoneplace.Thecave-makingrecipecallsfora steadyemissionofvolcanicgasandheataheavyannualsnowfallatan elevationhighenoughtokeepitfrommeltingduringthesummeranda bowl-shapedcratertoholdthesnow.??Snowaccumulatingyearlyin Rainier’ssummitcratersiscompactedandcompressedintoadenseformofice calledfirnasubstancemidwaybetweenordinaryiceandthedensercrystalline icethatmakesupglaciers.Heatrisingfromnumerousopeningscalled fumarolesalongtheinnercraterwallsmeltsoutchambersbetweentherocky wallsandtheoverlyingicepack.Circulatingcurrentsofwarmairthenmelt additionalopeninginthefirniceeventuallyconnectingtheindividual chambersandinthelargerofRainier’stwocratersformingacontinuous passagewaythatextendstwo-thirdsofthewayaroundthecrater’s interior.??Tomaintainthecavesystemtheelementsoffire undericemustremaininequilibriumEnoughsnowmustfillthecratereachyear toreplacethatmeltedfrombelow.Iftoomuchvolcanicheatisdischargedthe crater’sicepackwillmeltawayentirelyandthecaveswillvanishalongwith thesnowsofyesteryear.Iftoolittleheatisproducedtheicereplenished annuallybywintersnowstormswillexpandpushingagainsttheenclosingcrater wailsandsmotheringthepresentcavernsinsolidfirn ice.ThesecondparagraphmentionsallofthefollowingasnecessaryelementsinthecreationofsteamcavesEXCEPT______.
Duringhislifetimehewasableto{{U}}accumulate{{/U}}quiteafortune
{{*HTML*}}{{B}}第二篇{{/B}} ??Mostofthepioneersoflow-temperature physicsexpectedgasestoliquefybutnoneofthempredictedsuperconductivity. Thisphenomenonwasdiscoveredin1911byOnneswhilehewasstudyingfrozen mercury.??Morethan40yearspassedbeforephysicistswereable toofferanexplanationforsuperconductivity.Theacceptedtheorydevelopedin the1950sholdsthatthefundamentalbehaviorofelectronschangesatverylow temperaturesbecauseoftheeffectsofquantummechanics.Electronsaretiny particlesthatmakeuptheouterpartofanatomcirclingrapidlyaroundthe nucleusoftheatom.Inaregularconductor—ametalthatconductsanelectric current—theoutermostelectronsarenotboundtightlytotheatomsandsothey movearoundrelativelyfreely.Theflowoftheseelectronsisanelectric current.??Atnormaltemperaturesaconductor’selectronscannot movecompletelyfreelythroughthemetalbecausetheyarebumpedaroundbythe metal’satoms.Butaccordingtotheleadingtheoryofsuperconductivitywhena metalisverycoldelectronsformpairs.Thenlikecouplesmaneuveringona crowdeddancefloorbutnevercollidingthepairedelectronsareabletomove unimpededthroughthemetal.Inpairingupitseemstheelectronsareableto blendtogetherandmoveinunisonwithoutresistance.??This explanationseemstoaccountforsuperconductivityatextremelylow temperaturesbutin1986scientistsinSwitzerlandfoundthatsome metal-containingceramicsaresuperconductorsatmuchhighertemperatures.By 1992scientistshaddevelopedceramicsthatbecomesuperconductingat-297’F andsomeresearchersspeculatedthatroom-temperaturesuperconductorsmaybe possible.Scientistsarestilltryingtoformulateatheoryforhigh-temperature superconductivity.??Thenewceramicmaterialscanbemaintained attheirsuperconductingtemperatureswithrelativelyinexpensiveliquid nitrogenratherthanthemuchcolderandmuchmorecostlyliquidheliumrequired bymetalsuperconductors.Thecostdifferencecouldmakesuperconductivity practicalformanynewtechnologies.Forexamplemagneticallylevitatedtrains whichrequiresuperconductingelectromagnetswouldbemuchcheapertobuild thantheyarenow.Superconductingdevicesmightalsobeusedforadvancedpower transmissionlinesandinnewtypesofcompactultrafastcomputers.Butforthe timebeingsuperconductivityisfindingapplicationmostlyinscientific researchandinsomekindsofmedicalimaging devices.ThewordbumpinParagraph3maymean_______.
{{*HTML*}}阅读下面的短文文章中有5处空白文章后有6组文字请根据文章的内容选择5组文字将其分别放回文章原有位置以恢复文章原貌 ??Thereareabout350speciesofsharks.Thelargestsharksare thewhalesharkandthebaskingsharkwhichfeedonplanktonandsmallfish. Theadultwhalesharkgrowstoabout13meterslongwhilethebaskingshark extendsalittleover8meters.{{U}}?46?{{/U}}Ontheotherhandthere areanumberofthemwhichhaveattackedandkilledswimmers.Thesesharks includethegreathammerheadbluewhitetipandofcoursethegreatwhite shark.??{{U}}?47?{{/U}}Thegreatwhitegrowstobetween 5and8meterslongandcanweighmorethan1300kilograms.Itcanswimthrough theeateratspeedsreaching32kilometersperhour.Howeveroneofthefastest swimmersinthesharkfamilyisthebluesharkwhichcanswimataspeedof nearly752kilometersperhour.??{{U}}?48?{{/U}}They cangrowaslongas5centimetersandtheyareverysharp.Unlikehumanswho havetwosetsofteethintheirlifetimesomesharkscanhaveasmanyas5or 6sets.Itisrareforasharktohavefewerthan4sets.Itisrareforashark tohavefewerthan4sets.Astheshark’steetharewornouttheyfalloutand arereplacedbythenextrow.??{{U}}?49?{{/U}}Ina lifetimesomesharkscangrowandlosebetween10000and30000 teeth.??Seabiologistshavediscoveredthatthesharkhasa remarkablylargebrainandawell-developedsensorysystem.Theanimalhasan extraordinarysenseofsmellandexcellentvision.??{{U}} ?50?{{/U}}Specialsensorypitsontheshark’snoseandchincan detectweakelectricalfieldsinthewaterthatareproducedbyfishandother animals.Scientistshaveconcludedthatsharksassociatefoodwithelectrical fields.Scientistsalsobelievethatsharkscreatetheirownelectricalfields toaimtheminknowingwheretogointhesea.???A.Mustof thespeciesarenotparticularlycruel.???B.Sharkshave livedonearthformorethan180millionyears.???C.The greatwhiteisthelargestandcruelestofallanimalsknowntoattack humans.???D.Somesharkscanwearoutafullsetofteeth inlessthan6months.???E.Oneofthemostunusualaspects ofthesharkisitsteeth.???F.Butsharksarealso sensitivetoelectricalfields.{{*HTML*}}
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{{*HTML*}}{{B}}第三篇{{/B}} ??Volcanicfireandglacialiceare naturalenemies.Eruptionsatglaciatedvolcanoestypicallydestroyicefields astheydidin1980when70percentofMountSaintHelensicecoverwasde molished.Duringlongdormantintervalsglaciersgaintheupperhandcutting deeplyintovolcanicconesandeventuallyreducingthemtorubble.Onlyrarely dothesecompetingforcesofheatandcoldoperateinperfectbalancetocreate phenomenonsuchasthesteamcavesatMountRainierPark.? ?LocatedinsideRainier’stwoice-filledsummitcratersthesecavesforma labyrinthoftunnelsandvaultedchambersaboutoneandone-halfmilesintotal length.Theircreationdependsonanunusualcombinationoffactorsthatnature almostneverbringstogetherinoneplace.Thecave-makingrecipecallsfora steadyemissionofvolcanicgasandheataheavyannualsnowfallatan elevationhighenoughtokeepitfrommeltingduringthesummeranda bowl-shapedcratertoholdthesnow.??Snowaccumulatingyearlyin Rainier’ssummitcratersiscompactedandcompressedintoadenseformofice calledfirnasubstancemidwaybetweenordinaryiceandthedensercrystalline icethatmakesupglaciers.Heatrisingfromnumerousopeningscalled fumarolesalongtheinnercraterwallsmeltsoutchambersbetweentherocky wallsandtheoverlyingicepack.Circulatingcurrentsofwarmairthenmelt additionalopeninginthefirniceeventuallyconnectingtheindividual chambersandinthelargerofRainier’stwocratersformingacontinuous passagewaythatextendstwo-thirdsofthewayaroundthecrater’s interior.??Tomaintainthecavesystemtheelementsoffire undericemustremaininequilibriumEnoughsnowmustfillthecratereachyear toreplacethatmeltedfrombelow.Iftoomuchvolcanicheatisdischargedthe crater’sicepackwillmeltawayentirelyandthecaveswillvanishalongwith thesnowsofyesteryear.Iftoolittleheatisproducedtheicereplenished annuallybywintersnowstormswillexpandpushingagainsttheenclosingcrater wailsandsmotheringthepresentcavernsinsolidfirn ice.ThewordtheyPara.1Line2refersto______.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
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{{*HTML*}}下面有3篇短文每篇短文后有5道题每题后面有4个选项请仔细阅读短文并根据短文回答其后面的问题从4个选项中选择1个最佳答案 {{B}}第一篇{{/B}} ??Manyfeaturessimilartothose aeronauticalinnovationsdevelopedbymancanbeobservedamongstbirdsinsects andplants.Attimesobservationsofthesenaturalphenomenahaveinspiredman toimitatenatureandmodifyexistingdesigns.Atothertimesthenatural examplehasonlybeenrecognizedwellaftergreatamountsoftimeandvaluable materialshavebeendevotedtorefiningasimilarhumaninvention.? ?Birdsdeservecreditnotmerelyfordemonstratingflightwaspossiblebut forprovidingtemplatesfortheshapeofaircraftwings.Thewingsofbirds suggestedthepatternforleadingedgewingslotsthatimproveascentatslow speedsandforconicalcamberedwingtipsthatincreaseliftandstability.Other characteristicsofbirdwingssuchasatrailingedgeflaptoaidinsmooth landingswerenotrecognizedasimportantuntiltheyhadbeendesigned independentlybyaeronauticalengineers.Considerableresearcheffortin aeronauticscouldprobablyhavebeensavedbymorethoroughanalysisofbird flight.??Theinsectworldhasalsocontributedsignificantideas intherealmsofnavigationandguidance.Inordertoaidairlinenavigation duringtake-offsandlandingsunderadverseweatherconditionsengineers developedasystemforlocatingthesunwhenitwashiddenbycloudsthrough observingpolarizedlight—lightwhichtravelsinasingledirection.The researchwasinstigated鼓励激发afterstudiesofhoneybeesdemonstratedthatthey usedthismechanismtodeterminetheirlocationwhentheskywasdarkened.In anothercredittotheinsectworldtheevasiveguidancesystemsofcertain missilesuseangularaccelerationdetectorsmodeledafterthemulti-lensedeyes ofhouseflieswhichamplifysubtlemovementsbysplittingimagesintoa mosaic马赛克resemblingalargedisplayoftelevisionstunedtothesame channel.??Evenentitieswhichnevertakeflightthemselvesare responsibleforguidingthehandofaeronauticalengineers.Thewingedseedofa palmtreewasthemodelforanearlygliderandthesingle-wingedautorotating mapleseedwastheprototypeforameansofair-droppingcargoby parachute.ThewordtemplatesPara2isclosestinmeaningto______.
It'simpoliteto{{U}}cutin{{/U}}whentwopersonsareholdingaconversation.
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{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
{{*HTML*}}{{B}}第二篇{{/B}} ??Mostofthepioneersoflow-temperature physicsexpectedgasestoliquefybutnoneofthempredictedsuperconductivity. Thisphenomenonwasdiscoveredin1911byOnneswhilehewasstudyingfrozen mercury.??Morethan40yearspassedbeforephysicistswereable toofferanexplanationforsuperconductivity.Theacceptedtheorydevelopedin the1950sholdsthatthefundamentalbehaviorofelectronschangesatverylow temperaturesbecauseoftheeffectsofquantummechanics.Electronsaretiny particlesthatmakeuptheouterpartofanatomcirclingrapidlyaroundthe nucleusoftheatom.Inaregularconductor—ametalthatconductsanelectric current—theoutermostelectronsarenotboundtightlytotheatomsandsothey movearoundrelativelyfreely.Theflowoftheseelectronsisanelectric current.??Atnormaltemperaturesaconductor’selectronscannot movecompletelyfreelythroughthemetalbecausetheyarebumpedaroundbythe metal’satoms.Butaccordingtotheleadingtheoryofsuperconductivitywhena metalisverycoldelectronsformpairs.Thenlikecouplesmaneuveringona crowdeddancefloorbutnevercollidingthepairedelectronsareabletomove unimpededthroughthemetal.Inpairingupitseemstheelectronsareableto blendtogetherandmoveinunisonwithoutresistance.??This explanationseemstoaccountforsuperconductivityatextremelylow temperaturesbutin1986scientistsinSwitzerlandfoundthatsome metal-containingceramicsaresuperconductorsatmuchhighertemperatures.By 1992scientistshaddevelopedceramicsthatbecomesuperconductingat-297’F andsomeresearchersspeculatedthatroom-temperaturesuperconductorsmaybe possible.Scientistsarestilltryingtoformulateatheoryforhigh-temperature superconductivity.??Thenewceramicmaterialscanbemaintained attheirsuperconductingtemperatureswithrelativelyinexpensiveliquid nitrogenratherthanthemuchcolderandmuchmorecostlyliquidheliumrequired bymetalsuperconductors.Thecostdifferencecouldmakesuperconductivity practicalformanynewtechnologies.Forexamplemagneticallylevitatedtrains whichrequiresuperconductingelectromagnetswouldbemuchcheapertobuild thantheyarenow.Superconductingdevicesmightalsobeusedforadvancedpower transmissionlinesandinnewtypesofcompactultrafastcomputers.Butforthe timebeingsuperconductivityisfindingapplicationmostlyinscientific researchandinsomekindsofmedicalimaging devices.Thebestadvantageofnewceramicmaterialsovermetalsuperconductorsis______.
{{*HTML*}}下面有3篇短文每篇短文后有5道题每题后面有4个选项请仔细阅读短文并根据短文回答其后面的问题从4个选项中选择1个最佳答案 {{B}}第一篇{{/B}} ??Manyfeaturessimilartothose aeronauticalinnovationsdevelopedbymancanbeobservedamongstbirdsinsects andplants.Attimesobservationsofthesenaturalphenomenahaveinspiredman toimitatenatureandmodifyexistingdesigns.Atothertimesthenatural examplehasonlybeenrecognizedwellaftergreatamountsoftimeandvaluable materialshavebeendevotedtorefiningasimilarhumaninvention.? ?Birdsdeservecreditnotmerelyfordemonstratingflightwaspossiblebut forprovidingtemplatesfortheshapeofaircraftwings.Thewingsofbirds suggestedthepatternforleadingedgewingslotsthatimproveascentatslow speedsandforconicalcamberedwingtipsthatincreaseliftandstability.Other characteristicsofbirdwingssuchasatrailingedgeflaptoaidinsmooth landingswerenotrecognizedasimportantuntiltheyhadbeendesigned independentlybyaeronauticalengineers.Considerableresearcheffortin aeronauticscouldprobablyhavebeensavedbymorethoroughanalysisofbird flight.??Theinsectworldhasalsocontributedsignificantideas intherealmsofnavigationandguidance.Inordertoaidairlinenavigation duringtake-offsandlandingsunderadverseweatherconditionsengineers developedasystemforlocatingthesunwhenitwashiddenbycloudsthrough observingpolarizedlight—lightwhichtravelsinasingledirection.The researchwasinstigated鼓励激发afterstudiesofhoneybeesdemonstratedthatthey usedthismechanismtodeterminetheirlocationwhentheskywasdarkened.In anothercredittotheinsectworldtheevasiveguidancesystemsofcertain missilesuseangularaccelerationdetectorsmodeledafterthemulti-lensedeyes ofhouseflieswhichamplifysubtlemovementsbysplittingimagesintoa mosaic马赛克resemblingalargedisplayoftelevisionstunedtothesame channel.??Evenentitieswhichnevertakeflightthemselvesare responsibleforguidingthehandofaeronauticalengineers.Thewingedseedofa palmtreewasthemodelforanearlygliderandthesingle-wingedautorotating mapleseedwastheprototypeforameansofair-droppingcargoby parachute.Researchrelatedtomissileguidancesystemsimpliesthat______.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
{{*HTML*}}阅读下面的短文文章中有5处空白文章后有6组文字请根据文章的内容选择5组文字将其分别放回文章原有位置以恢复文章原貌 ??Thereareabout350speciesofsharks.Thelargestsharksare thewhalesharkandthebaskingsharkwhichfeedonplanktonandsmallfish. Theadultwhalesharkgrowstoabout13meterslongwhilethebaskingshark extendsalittleover8meters.{{U}}?46?{{/U}}Ontheotherhandthere areanumberofthemwhichhaveattackedandkilledswimmers.Thesesharks includethegreathammerheadbluewhitetipandofcoursethegreatwhite shark.??{{U}}?47?{{/U}}Thegreatwhitegrowstobetween 5and8meterslongandcanweighmorethan1300kilograms.Itcanswimthrough theeateratspeedsreaching32kilometersperhour.Howeveroneofthefastest swimmersinthesharkfamilyisthebluesharkwhichcanswimataspeedof nearly752kilometersperhour.??{{U}}?48?{{/U}}They cangrowaslongas5centimetersandtheyareverysharp.Unlikehumanswho havetwosetsofteethintheirlifetimesomesharkscanhaveasmanyas5or 6sets.Itisrareforasharktohavefewerthan4sets.Itisrareforashark tohavefewerthan4sets.Astheshark’steetharewornouttheyfalloutand arereplacedbythenextrow.??{{U}}?49?{{/U}}Ina lifetimesomesharkscangrowandlosebetween10000and30000 teeth.??Seabiologistshavediscoveredthatthesharkhasa remarkablylargebrainandawell-developedsensorysystem.Theanimalhasan extraordinarysenseofsmellandexcellentvision.??{{U}} ?50?{{/U}}Specialsensorypitsontheshark’snoseandchincan detectweakelectricalfieldsinthewaterthatareproducedbyfishandother animals.Scientistshaveconcludedthatsharksassociatefoodwithelectrical fields.Scientistsalsobelievethatsharkscreatetheirownelectricalfields toaimtheminknowingwheretogointhesea.???A.Mustof thespeciesarenotparticularlycruel.???B.Sharkshave livedonearthformorethan180millionyears.???C.The greatwhiteisthelargestandcruelestofallanimalsknowntoattack humans.???D.Somesharkscanwearoutafullsetofteeth inlessthan6months.???E.Oneofthemostunusualaspects ofthesharkisitsteeth.???F.Butsharksarealso sensitivetoelectricalfields.
OfalltheplanetsinthissolarsystemMercuryis{{U}}nearest{{/U}}theSun.
Almostalleconomistsagreethatnations{{U}}gain{{/U}}bytradingwithoneanother.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
Theshootsystemofperennialscanhelptheplantsabsorblessofthesun'sray.
{{*HTML*}}阅读下面的短文文中有15处空白每处空白给出4个选项请根据短文的内容从4个选项中选择1个最佳答案 ??Energyequalsmasstimesthespeedof lightsquared.ThisisthefamousequationofAlbertEinstein.It{{U}}?51 ?{{/U}}tothecategoryofthetheoryofrelativityanditequatesenergy withmass.??Allthingsaremadeupofatoms.When{{U}}?52 ?{{/U}}ofanatomtravelsatalmostthespeedoflight{{U}}?53 ?{{/U}}weputmoreenergyintoittoincreasethespeeditbeginstoin creaseinmass.Theenergythatmakesittravelfastcannotmakeittravel{{U}} ?54?{{/U}}thespeedoflight—nothing{{U}}?55?{{/U}}light cantravelthatfast-sotheenergygoesintothething{{U}}?56 ?{{/U}}andincreasesitsmass.Energy{{U}}?57?{{/U}}into mass.??Whyisthetheorycalledthetheoryofrelativity?Athing thatisrelativedependsupon{{U}}?58?{{/U}}elsetoidentifyitorto defineit.Inrelativitytheoryweidentifyordefinemasstimeandlength{{U}} ?59?{{/U}}tothespeedoflight.??Whensomethingisat restitlooks{{U}}?60?{{/U}}inlength.Howeverwhenittravelsat almostthespeedoflightitbecomes{{U}}?61?{{/U}}.Timealso changes.Howeverthechangeintimeis{{U}}?62?{{/U}}tothechangein length.Thelengthofathingbecomesshort{{U}}?63?{{/U}}timebecomes long.??Ifyouwantto{{U}}?64?{{/U}}youngrelativeto afriendtakeatripinaspaceshipthattravelsat{{U}}?65?{{/U}}the speedoflight.Andalthoughtimeandheartbeatseemordinarytoyouinthe spaceshipwhenyoureturnlookatyourfriend;Relativetoyouheorsheis old.
{{*HTML*}}{{B}}第二篇{{/B}} ??Mostofthepioneersoflow-temperature physicsexpectedgasestoliquefybutnoneofthempredictedsuperconductivity. Thisphenomenonwasdiscoveredin1911byOnneswhilehewasstudyingfrozen mercury.??Morethan40yearspassedbeforephysicistswereable toofferanexplanationforsuperconductivity.Theacceptedtheorydevelopedin the1950sholdsthatthefundamentalbehaviorofelectronschangesatverylow temperaturesbecauseoftheeffectsofquantummechanics.Electronsaretiny particlesthatmakeuptheouterpartofanatomcirclingrapidlyaroundthe nucleusoftheatom.Inaregularconductor—ametalthatconductsanelectric current—theoutermostelectronsarenotboundtightlytotheatomsandsothey movearoundrelativelyfreely.Theflowoftheseelectronsisanelectric current.??Atnormaltemperaturesaconductor’selectronscannot movecompletelyfreelythroughthemetalbecausetheyarebumpedaroundbythe metal’satoms.Butaccordingtotheleadingtheoryofsuperconductivitywhena metalisverycoldelectronsformpairs.Thenlikecouplesmaneuveringona crowdeddancefloorbutnevercollidingthepairedelectronsareabletomove unimpededthroughthemetal.Inpairingupitseemstheelectronsareableto blendtogetherandmoveinunisonwithoutresistance.??This explanationseemstoaccountforsuperconductivityatextremelylow temperaturesbutin1986scientistsinSwitzerlandfoundthatsome metal-containingceramicsaresuperconductorsatmuchhighertemperatures.By 1992scientistshaddevelopedceramicsthatbecomesuperconductingat-297’F andsomeresearchersspeculatedthatroom-temperaturesuperconductorsmaybe possible.Scientistsarestilltryingtoformulateatheoryforhigh-temperature superconductivity.??Thenewceramicmaterialscanbemaintained attheirsuperconductingtemperatureswithrelativelyinexpensiveliquid nitrogenratherthanthemuchcolderandmuchmorecostlyliquidheliumrequired bymetalsuperconductors.Thecostdifferencecouldmakesuperconductivity practicalformanynewtechnologies.Forexamplemagneticallylevitatedtrains whichrequiresuperconductingelectromagnetswouldbemuchcheapertobuild thantheyarenow.Superconductingdevicesmightalsobeusedforadvancedpower transmissionlinesandinnewtypesofcompactultrafastcomputers.Butforthe timebeingsuperconductivityisfindingapplicationmostlyinscientific researchandinsomekindsofmedicalimaging devices.Theflowofanelectriccurrentinaregularconductorismadepossiblebythefactthat______.
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