考研英语专项训练题及答案.docx
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考研英语专项训练题及答案.docx
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考研英语专项训练题及答案
XX年考研英语专项训练题及答案
Althoughrecentyearshaveseensubstantialreductionsinnoxiouspollutantsfromindividualmotorvehicles,thenumberofsuchvehicleshasbeensteadilyincreasing.Consequently,morethan100citiesintheUnitedStatesstillhavelevelsofcarbonmonoxide,particulatematter,andozone(generatedbyphotochemicalreactionswithhydrocarbonsfromvehicleexhaust)thatexceedlegallyestablishedlimits.Thereisagrowingrealizationthattheonlyeffectivewaytoachievefurtherreductionsinvehicleemissions—shortofamassiveshiftawayfromtheprivateautomobile—istoreplaceconventionaldieselfuelandgasolinewithcleaner-burningfuelssuchaspressednaturalgas,liquefiedpetroleumgas,ethanol,ormethanol.
Allofthesealternativesarecarbon-basedfuelswhosemoleculesaresmallerandsimplerthanthoseofgasoline.Thesemoleculesburnmorecleanlythangasoline,inpartbecausetheyhavefewer,ifany,carbon-carbonbondsandthehydrocarbonstheydoemitarelesslikelytogenerateozone.Thebustionoflargermolecules,whichhavemultiplecarbon-carbonbondsinvolvesamoreplexseriesofreactions.Thesereactionsincreasetheprobabilityofinpletebustionandaremorelikelytoreleaseunbustedandphotochemicallyactivehydrocarbonpoundsintotheatmosphere.Ontheotherhand,alternativefuelsdohavedrawbacks.Compressednaturalgaswouldrequirethatvehicleshavesetofheavyfueltanks—aseriousliabilityintermsofperformanceandfuelefficiency—andliquefiedpetroleumgasfacesfundamentallimitsonsupply.
Ethanolandmethanol,ontheotherhand,haveimportantadvantagesoverothercarbon-basedalternativefuels:
theyhavehigherenergycontentpervolumeandwouldrequireminimalchangesintheexistingworkfordistributingmotorfuel.Ethanolismonlyusedasagasolinesupplement,butitiscurrentlyabouttwiceasexpensiveasmethanol,thelowcostofwhichisoneofitsattractivefeatures.Methanol’smostattractivefeature,however,isthatitcanreducebyabout90percentthevehicleemissionsthatformozone,themostseriousurbanairpollutant.
Likeanyalternativefuel,methanolhasitscritics.Yetmuchofthecriticismisbasedontheuseof“gasolineclone”vehiclesthatdonotincorporateeventhesimplestdesignimprovementsthataremadepossiblewiththeuseofmethanol.Itistrue,forexample,thatagivenvolumeofmethanolprovidesonlyaboutone-halfoftheenergythatgasolineanddieselfueldo;otherthingsbeingequal,thefueltankwouldhavetobesomewhatlargerandheavier.However,sincemethanol-fueledvehiclescouldbedesignedtobemuchmoreefficientthan“gasolineclone”vehiclesfueledwithmethanoltheywouldneedparativelylessfuel.Vehiclesincorporatingonlythesimplestoftheengineimprovementsthatmethanolmakesfeasiblewouldstillcontributetoanimmediatelesseningofurbanairpollution.
1.Theauthorofthetextisprimarilyconcernedwith
[A]counteringaflawedargumentthatdismissesapossiblesolutiontoaproblem.
[B]reconcilingcontradictorypointsofviewaboutthenatureofaproblem.
[C]identifyingthestrengthsofpossiblesolutionstoaproblem.
[D]discussingaproblemandarguinginfavorofonesolutiontoit.
2.Aordingtothetext,inpletebustionismorelikelytoourwithgasolinethanwithanalternativefuelbecause
[A]thebustionofgasolinereleasesphotochemicallyactivehydrocarbons.
[B]thebustionofgasolineembracesanintricatesetofreactions.
[C]gasolinemoleculeshaveasimplemolecularstructure.
[D]gasolineisposedofsmallmolecules.
3.Thetextsuggestswhichofthefollowingaboutairpollution?
[A]Furtherattemptstoreduceemissionsfromgasoline-fueledvehicleswillnothelplowerurbanair-pollutionlevels.
[B]Attemptstoreducethepollutantsthatanindividualgasoline-fueledvehicleemitshavebeenlargelyunsuessful.
[C]Fewseriousattemptshavebeenmadetoreducetheamountofpollutantsemittedbygasoline-fueledvehicles.
[D]Pollutantsemittedbygasoline-fueledvehiclesarenotthemostcriticalsourceofurbanairpollution.
4.Whichofthefollowingmostcloselyparallelsthesituationdescribedinthefirstsentenceofthetext?
[A]Althoughatownreducesitspublicservicesinordertoavoidataxincrease,thetown’staxrateexceedsthatofothertownsinthesurroundingarea.
[B]Althoughastatepassesstrictlawstolimitthetypeoftoxicmaterialthatcanbedisposedofinpubliclandfills,illegaldumpingcontinuestoincrease.
[C]Althoughatown’scitizensreducetheirindividualuseofwater,thetown’swatersuppliescontinuetodwindlebecauseofasteadyincreaseinthetotalpopulatingofthetown.
[D]Althoughacountryattemptstoincreasethesaleofdomesticgoodsbyaddingataxtothepriceofimportedgoods,thesaleofimportedgoodswithinthecountrycontinuestoincrease.
5.Itcanbeinferredthattheauthorofthetextmostlikelyregardsthecriticismofmethanolas
[A]flawedbecauseoftheassumptionsonwhichitisbased.
[B]inapplicablebecauseofaninconsistencyinthecritics’arguments.
[C]misguidedbecauseofitsexclusivelytechnologicalfocus.
[D]inauratebecauseitignoresconsumers’concerns.
1.【答案】C
【考点解析】这是一道中心主旨题。
本文的中心主旨句是首段的尾句。
通过对首段尾句以及其它段落主题句的阅读和理解,可以推导出此题的正确选项是C。
考生在破解此类题型时一定要首先抓住原文的中心主旨句以及各段的主题句。
2.【答案】B
【考点解析】此题是一道指代词题型。
根据题干中的“inpletebustion”可将此题的答案信息迅速确定在第二段的第四句,该句中的指代词“these”暗示此题的详细答案信息应该在第二段的第三句。
通过阅读和理解第二段的第三句可推导出此题的正确选项是B。
考生在解题时对指代词一定要认真理解。
3.【答案】A
【考点解析】此题是一道审题定位题型。
通过题干中的“airpollution”可将此题的答案信息迅速确定在第一段,因为第一段首句中含有“noxiouspollutants”,都在谈污染的问题。
通过阅读和理解第一段,尤其是第一段尾句即全文的中心主旨句,可推导出此题的正确选项是A。
这是一道比拟难的题。
考生在解题时一定要具备审题定位能力,还要具备归纳和推导能力。
4.【答案】C
【考点解析】这是一道类比题型,因为此题题干中含有“parallels”(与……相当,与……一样)一词。
此题题干已将类比的参照对象确定在第一段的首句。
通过仔细阅读和理解第一段的首句,可推导出此题的正确选项是C,因为该选项涉及的增减关系的前提条件和原文一脉相承。
考生在破解这种题型时应对原文所表达的内容与关系有明确的认识和把握,不可以无根据地推导。
5.【答案】A
【考点解析】这是一道细节推导题型。
此题题干中的“thecriticismofmethanol”把此题的答案信息确定在第四段的第一、二句。
通过阅读和理解这两句话,尤其是第二句话,就可推导出此题的正确选项A。
考生在破解此题时一定要注意第二句话的第一个词“Yet”在语意上所起的作用。
考生在解题时一定要重视启承转合词的出现和功能。
近年来,尽管单个机动车辆排放的有毒污染物已大幅减少,但这些机动车辆的数量一直在持续增长,结果是,在美国有100多个城市的大气中一氧化碳、灰尘和臭氧(由车辆尾气中的碳氢化合物经光化反响产生)的含量已超出了法定的限度。
人们愈来愈认识到,实现车辆废气进一步减少而又不必大规模减少私家轿车的唯一有效途径是用清洁燃料来代替传统的柴油和汽油燃料。
这些清洁燃料包括压缩天然气、液化石油气、乙醇和甲醇。
所有这些替代产品都是碳基燃料,不过它们的分子要比汽油的分子小且简单。
它们可以比汽油燃烧得更彻底,局部原因在于,即使它们含有碳—碳化学键,含量也较少,而且它们释放的碳氢化合物也不大可能产生臭氧。
那些具有多重碳——碳化学键的大分子在燃烧时包含了一系列复杂的反响。
这些反响增大了不完全燃烧的可能,并且更容易释放未燃烧的碳氢化合物,而这些化合物又对光化学反响很活泼。
另一方面,这些替代燃料也有自己的缺点。
压缩天然气可能需要车辆配备一个笨重的油箱,这对车辆性能和燃料效率又极为不利,并且液化石油气还面临着供给上的根本限制。
从另一方面来看,甲醇和乙醇与其它的碳基替代燃料相比有重要的益处:
它们具有单位体积更高的能量含量,而且对现存的燃料销售网络只需很小地改变。
乙醇通常作为汽油的替代品,但目前它比甲醇要贵两倍,因此甲醇的低廉价格便成为引人注目的特点。
然而,甲醇最吸引人的特点还在于它可以减少90%形成臭氧的废气,而臭氧又是城市中最严重的污染物。
和其它的替代燃料一样,甲醇也遭到了非难。
可大多数批评都建立在使用“汽油系列”的车辆不进展最简单的设计改良以可能使用甲醇燃料的根底上。
例如,事实上一定体积的甲醇和同体积的汽油和柴油相比,只能提供相当于它们大约一半的能量。
在其它因素相同的条件下,油箱可能要大一点和重一点,然而,由于甲醇燃料的车辆可以设计得比使用甲醇的“汽油系列”车辆还要高效,它们可能需要更少的燃料。
同时,对发动机进展最简单的改良便可使用甲醇的车辆,这将对城市大气污染的迅速减轻做出奉献。
Oneofthesimplestandbestknownkindsofcrystalistheionicsalt,ofwhichatypicalexampleissodiumchloride,orordinarytablesalt.Thefundamentalponentsofanionicsaltareions:
atomsormoleculesthathavebeeelectricallychargedbygainingorlosingonemoreelectrons.Informingsodiumchloride,forexample,sodiumatomsgiveupanelectron(therebybeingpositivelycharged)andchlorineatomsgainanelectron(therebybeingnegativelycharged).Theionsareattractedtooneanotherbytheiroppositecharges,andtheystacktogetherpactly,liketightlypackedspheres.
Recently,scientistsatMichiganStateUniversitycreatedanewkindofcrystalcalledanelectride.Inelectrides,theanions(negativeions)arepletelyreplacedbyelectrons,whicharetrappedinnaturallyformedcavitieswithinaframeworkofregularlystackedcations(positiveions).Electridesarethefirstexamplesofionicsaltsinwhichalltheseanionicsitesareoupiedsolelybyelectrons.
Unlikeothertypesofanions,anionicelectronsdonotbehaveasiftheyweresimplechargedspheres.Inparticular,becauseoftheirlowmassandtheirtendencytointeractwithoneanotherovergreatdistances,theycannotbe“pinneddown”toanyonelocation.Instead,theywanderclosetoandamongtheatomsliningthecavityandinteractwithelectronsinnearbycavities,perhapschangingplaceswiththem.
Thepropertiesofanelectridedependlargelyonthedistancebetweenthecavitiesthatholdtrappedelectrons.Whenthetrappedelectronsarefarapart,theydonotinteractstrongly,andsobehavesomewhatlikeanarrayofisolatednegativecharges.Whentheyareclosertogether,theybegintodisplaypropertiesassociatedwithlargeensemblesofidenticalparticles.Whentheyarestillcloser,theensemblepropertiesdominateandtheelectrons“delocalize”:
theyarenolongertightlyboundwithinindividualcavitiesbutaremoreorlessfreetopassthroughthespaceswithintheframeworkofpositiveions.
Bysynthesizingelectridesfromavarietyofmaterials,onecanvarythegeometryoftheanioniccavitiesandtheirrelationtothesurroundingcations.Theresultingpropertiesmaymakeitpossibleforelectridestobeeabasisforeconomicallyusefulnewmaterialsanddevices.Forinstance,becausetheelectronsinsomeelectridesareveryweaklybound,thesecrystalscouldbeeffectiveasphotosensitivedetectors,inwhichanimpingingphotonliberatesanelectron,resultinginasmallelectriccurrent.Thesameweakbindingcouldalsomakeelectridesusefulinsolarenergyconvertersandascathodesinbatteries.Oneobstacleisthetendencyofelectridestodeposethroughreactionwithairandwater.Researchersareseekingwaystoincreasetheirstability.
1.Thetext
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