高考英语最值得背诵的英语文章精粹.docx

高考英语最值得背诵的英语文章精粹1CellsandTemperature Cellscannotremainaliveoutsidecertainlimitsoftemperatureandmuchnarrowerlimitsmarktheboundariesofeffectivefunctioning.Enzymesystemsofmammalsandbirdsaremostefficientonlywithinanarrowrangearound37C;adepartureofafewdegreesfromthisvalueseriouslyimpairstheirfunctioning.Eventhoughcellscansurvivewiderfluctuationstheintegratedactionsofbodilysystemsareimpaired.Otheranimalshaveawidertoleranceforchangesofbodilytemperature. Forcenturiesithasbeenrecognizedthatmammalsandbirdsdifferfromotheranimalsinthewaytheyregulatebodytemperature.Waysofcharacterizingthedifferencehavebecomemoreaccurateandmeaningfulovertime,butpopularterminologystillreflectstheolddivisioninto“warm-blooded”and“cold-blooded”species;warm-bloodedincludedmammalsandbirdswhereasallothercreatureswereconsideredcold-blooded.Asmorespecieswerestudied,itbecameevidentthatthisclassificationwasinadequate.Afencelizardoradesertiguanaeachcold-blooded-usuallyhasabodytemperatureonlyadegreeortwobelowthatofhumansandsoisnotcold.Thereforethenextdistinctionwasmadebetweenanimalsthatmaintainaconstantbodytemperature,calledhome0therms,andthosewhosebodytemperaturevarieswiththeirenvironments,calledpoikilotherms.Butthisclassificationalsoprovedinadequate,becauseamongmammalstherearemanythatvarytheirbodytemperaturesduringhibernation.Furthermore,manyinvertebratesthatliveinthedepthsoftheoceanneverexperiencechangeinthedepthsoftheoceanneverexperiencechangeinthechillofthedeepwater,andtheirbodytemperaturesremainconstant. 2Sleep Sleetispartofapersonsdailyactivitycycle.Thereareseveraldifferentstagesofsleep,andtheytoooccurincycles.Ifyouareanaveragesleeper,yoursleepcycleisasfollows.Whenyoufistdriftoffintoslumber,youreyeswillrollaboutabit,youtemperaturewilldropslightly,yourmuscleswillrelax,andyourbreathingwellslowandbecomequiteregular.Yourbrainwavesslowandbecomequiteregular.Yourbrainwavesslowdownabittoo,withthealpharhythmofratherfastwaves1sleep.Forthenexthalfhourorso,asyourelaxmoreandmore,youwilldriftdownthroughstage2andstage3sleep.Theloweryourstageofsleep.sloweryourbrainwaveswillbe.Thenabout40to69minutesafteryouloseconsciousnessyouwillhavereachedthedeepestsleepofall.Yourbrainwillshowthelargeslowwavesthatareknownasthedeltarhythm.Thisisstage4sleep. Youdonotremainatthisdeepfourthstageallnightlong,butinsteadabout80minutesafteryoufallintoslumber,yourbrainactivitylevelwillincreaseagainslightly.Thedeltarhythmwilldisappear,tobereplacedbytheactivitypatternofbrainwaves.Youreyeswillbegintodartaroundunderyourclosedeyelidsasifyouwerelookingatsomethingoccurringinfrontofyou.Thisperiodofrapideyemovementlastsforsome8to15minutesandiscalledREMsleep.ItisduringREMsleepperiod,yourbodywillsoonrelaxagain,yourbreathingwillslipgentlybackfromstage1tostage4sleep-onlytoriseonceagaintothesurfaceofnearconsciousnesssome80minuteslater. 3Bacteria Bacteriaareextremelysmalllivingthings.Whilewemeasureourownsizesininchesorcentimeters,bacterialsizeismeasuredinmicrons.Onemicronisathousandthofamillimeter:apinheadisaboutamillimeteracross.Rod-shapedbacteriaareusuallyfromtwotofourmicronslong,whileroundedonesaregenerallyonemicronindiameter.Thusifyouenlargedaroundedbacteriumathousandtimes,itwouldbejustaboutthesizeofapinhead.Anadulthumanmagnifiedbythesameamountwouldbeoveramile(1.6kilometer)tall. Evenwithanordinarymicroscope,youmustlookcloselytoseebacteria.Usingamagnificationof100times,onefindsthatbacteriaarebarelyvisibleastinyrodsordots.Onecannotmakeoutanythingoftheirstructure.Usingspecialstains,onecanseethatsomebacteriahaveattachedtothemwavy-looking“hairs”calledflagella.Othershaveonlyoneflagellum.Theflagellarotate,pushingthebacteriathroughthewater.Manybacterialackflagellaandcannotmoveaboutbytheirownpower,whileotherscanglidealongoversurfacesbysomelittle-understoodmechanism. Fromthebacteriapointofview,theworldisaverydifferentplacefromwhatitistohumans.Toabacteriumwaterisasthickasmolassesistous.Bacteriaaresosmallthattheyareinfluencedbythemovementsofthechemicalmoleculesaroundthem.Bacteriaunderthemicroscope,eventhosewithnoflagella,oftenbounceaboutinthewater.Thisisbecausetheycollidewiththewaterymoleculesandarepushedthiswayandthat.Moleculesmovesorapidlythatwithinatenthofasecondthemoleculesaroundabacteriahaveallbeenreplacedbynewones;evenbacteriawithoutflagellaarethusconstantlyexposedtoachangingenvironment. 4FolkCultures Afolkcultureisasmallisolated,cohesive,conservative,nearlyself-sufficientgroupthatishomogeneousincustomandracewithastrongfamilyorclanstructureandhighlydevelopedrituals.Orderismaintainedthroughsanctionsbasedinthereligionorfamilyandinterpersonal.Relationshipsarestrong.Traditionisparamount,andchangecomesinfrequentlyandslowly.Thereisrelativelylittledivisionoflaborintospecializedduties.Rather,eachpersonisexpectedtoperformagreatvarietyoftasks,thoughdutiesmaydifferbetweenthesexes.Mostgoodsarehandmadeandsubsistenceeconomyprevails.Individualismisweaklydevelopedinfolkculturesasaresocialclasses.UnalteredfolkculturesnolongerexistinindustrializedcountriessuchastheUnitedStatesandCanada.PerhapsthenearestmodernequivalentinAngloAmericaistheAmish,aGermanAmericanfarmingsectthatlargelyrenouncestheproductsandlaborsavingdevicesoftheindustrialage.InAmishareas,horsedrawnbuggiesstillserveasalocaltransportationdeviceandthefaithfularenotpermittedtoownautomobiles.TheAmishscentralreligiousconceptofDemut“humility”,clearlyreflectstheweaknessofindividualismandsocialclasssotypicaloffolkculturesandthereisacorrespondingstrengthofAmishgroupidentity.RarelydotheAmishmarryoutsidetheirsect.Thereligion,avarietyoftheMennonitefaith,providestheprincipalmechanismformaintainingorder. Bycontrastapopularcultureisalargeheterogeneousgroupoftenhighlyindividualisticandapronouncedmanyspecializedprofessions.Secularinstitutionsofcontrolsuchasthepoliceandarmytaketheplaceofreligionandfamilyinmaintainingorder,andamoney-basedeconomyprevails.Becauseofthesecontrasts,“popular”maybeviewedasclearlydifferentfrom“folk”.Thepopularisreplacingthefolkinindustrializedcountriesandinmanydevelopingnations.Folk-madeobjectsgivewaytotheirpopularequivalent,usuallybecausethepopularitemismorequicklyorcheaplyproduced,iseasierortimesavingtouseorleadsmoreprestigetotheowner. 5Vision Humanvisionlikethatofotherprimateshasevolvedinanarborealenvironment.Inthedensecomplexworldofatropicalforest,itismoreimportanttoseewellthattodevelopanacutesenseofsmell.Inthecourseofevolutionmembersoftheprimatelinehaveacquiredlargeeyeswhilethesnouthasshrunktogivetheeyeanunimpededview.Ofmammalsonlyhumansandsomeprimatesenjoycolorvision.Theredflagisblacktothebull.Horsesliveinamonochromeworld.lightvisibletohumaneyeshoweveroccupiesonlyaverynarrowbandinthewholeelectromagneticspectrum.Ultravioletraysareinvisibletohumansthoughantsandhoneybeesaresensitivetothem.Humansthoughantsandhoneybeesaresensitivetothem.Humanshavenodirectperceptionofinfraredraysunliketherattlesnakewhichhasreceptorstunedintowavelengthslongerthan0.7micron.Theworldwouldlookeerilydifferentifhumaneyesweresensitivetoinfraredradiation.Theninsteadofthedarknessofnight,wewouldbeabletomoveeasilyinastrangeshadowlessworldwhereobjectsglowedwithvaryingdegreesofintensity.Buthumaneyesexcelinotherways.Theyareinfactremarkablydiscerningincolorgradation.Thecolorsensitivityofnormalhumanvisionisrarelysurpassedevenbysophisticatedtechnicaldevices. 6ThesourceofEnergy Asummaryofthephysicalandchemicalnatureoflifemustbegin,notontheEarth,butintheSun;infact,attheSunsverycenter.ItisherethatistobefoundthesourceoftheenergythattheSunconstantlypoursoutintospaceaslightandheat.ThisenergyislibratedatthecenteroftheSunasbillionsuponbillionsofnucleiofhydrogenatomscollidewitheachotherandfusetogethertoformnucleiofhelium,andindoingso,releasesomeoftheenergythatisstoredinthenucleiofatoms.TheoutputoflightandheatoftheSunrequiresthatsome600milliontonsofhydrogenbeconvertedintoheliumintheSuneverysecond.ThistheSunhasbeendoingforseveralthousandsofmillionsofyear. ThenuclearenergyisreleasedattheSunscenterashigh-energygammaradiation,aformofelectromagneticradiationlikelightandradiowaves,onlyofverymuchshorterwavelength.ThisgammaradiationisabsorbedbyatomsinsidetheSuntobereemittedatslightlylongerwavelengths.Thisradiation,initsturnisabsorbedandreemitted.Astheenergyfiltersthroughthelayersofthesolarinterior,itpassesthroughtheX-raypartofthespectrumeventuallybecominglight.Atthisstage,ithasreachedwhatwecallthesolarsurface,andcanescapeintospacewithoutbeingabsorbedfurtherbysolaratoms.AverysmallfractionoftheSunslightandheatisemittedinsuchdirectionsthatafterpassingunhinderedthroughinterplanetaryspace,ithitstheEarth. 7ObtainingFreshwaterfromicebergs Theconceptofobtainingfreshwaterfromicebergsthataretowedtopopulatedareasandaridregionsoftheworldwasoncetreatedasajokemoreappropriatetocartoonsthanreallife.Butnowitisbeingconsideredquiteseriouslybymanynations,especiallysincescientistshavewarnedthatthehumanracewilloutgrowitsfreshwatersupplyfasterthanitrunsoutoffood. Glaciersareapossiblesourceoffreshwaterthathasbeenoverlookeduntilrecently.Three-quartersoftheEarthsfreshwatersupplyisstilltiedupinglacialice,areservoirofuntappedfreshwatersoimmensethatitcouldsustainalltheriversoftheworldfor1,000years.Floatingontheoceanseveryyearare7,659trillionmetrictonsoficeencasedin10000icebergsthatbreakawayfromthepolaricecaps,morethanninetypercentofthemfromAntarctica. Hugeglaciersthatstretchovertheshallowcontinentalshelfgivebirthtoicebergsthroughouttheyear.Icebergsarenotlikeseaice,whichisformedwhentheseaitselffreezes,rather,theyareformedentirelyonland,breakingoffwhenglaciersspreadoverthesea.Astheydriftawayfromthepolarregion,icebergssometimesmovemysteriouslyinadirectionoppositetothewind,pulledbysubsurfacecurrents.Becausetheymeltmoreslowlythansmallerpiecesofice,icebergshavebeenknowntodriftasfarnorthas35degreessouthoftheequatorintheAtlanticOcean.Tocorralthemandsteerthemtopartsoftheworldwheretheyareneededwouldnotbetoodifficult. Thedifficultyarisesinothertechnicalmatters,suchasthepreventionofrapidmeltinginwarmerclimatesandthefunnelingoffreshwatertoshoreingreatvolume.Buteveniftheicebergslosthalfoftheirvolumeintowing,thewatertheycouldprovidewouldbefarcheaperthanthatproducedbydesalinization,orremovingsaltfromwater. 8Statistics Thereweretwowidelydivergentinfluencesontheearlydevelopmentofstatisticalmethods.Statisticshadamotherwhowasdedicatedtokeepingorderlyrecordsofgovernmentunits(statesandstatisticscomefromthesameLatinrootstatus)andagentlemanlygamblingfatherwhoreliedonmathematicstoincreasehisskillatplayingtheoddsingamesofchance.Theinfluenceofthemotherontheoffspring,statistics,isrepresentedbycounting,measuring,describing,tabulating,ordering,andthetakingofcensusesallofwhichledtomoderndescriptivestatistics.Fromtheinfluenceofthefathercamemoderninferentialstatistics,whichisbasedsquarelyontheoriesofprobability. Describingcollectionsinvolvestabulating,depictinganddescribingcollectionsofdata.Thesedatamaybequantitativesuchasmeasuresofheight,intelligenceorgradelevel-variablesthatarecharacterizedbyanunderlyingcontinuum-orthedatamayrepresentqualitativevariables,suchassex,collegemajororpersonalitytype.Largemassesofdatamustgenerallyundergoaprocessofsummarizationorreductionbeforetheyarecomprehensible.Descriptivestatisticsisatoolfordescribingorsummarizingorreducingtocomprehensibleformthepropertiesofanotherwiseunwieldymassofdata. Inferentialstatisticsisaformalizedbodyofmethodsforsolvinganotherclassofproblemsthatpresentgreatofproblemscharacteristicallyinvolvesattemptstomakepredictionsusingasampleofobservations.Forexample,aschoolsuperintendentwishestodeterminetheproportionofchildreninalargeschoolsystemwhocometoschoolwithoutbreakfast,havebeenvaccinatedforflu,orwhatever.Havingalittleknowledgeofstatistics,thesuperintendentwouldknowthatitisunnecessaryandinefficienttoquestioneachchild:theproportionforthesampleofasfewas100children.Thus,thepurposeofinferentialstatisticsistopredictorestimatecharacteristicsofapopulationfromaknowledgeofthecharacteristicsofonlyasampleofthepopulation. 9Coal-firedpowerplants TheinventionoftheincandescentlightbulbbyThomasA.Edisonin1879createdademandforacheap,readilyavailablefuelwithwhichtogeneratelargeamountsofelectricpower.Coalseemedtofitthebill,anditfueledtheearliestpowerstations.(whichweresetupattheendofthenineteenthcenturybyEdisonhimself).Asmorepowerplantswereconstructedthroughoutthecountry,therelianceoncoalincreasedthroughoutthecountry,therelianceoncoalincreased.SincetheFirstWorldWar,coal-firedpowerplantshadacombinedintheUnitedStateseachyear.In1986suchplantshadacombinedgeneratingcapacityof289,000megawattsandconsumed83percentofthenearly900milliontonsofcoalminedinthecountrythatyear.Giventheuncertaintyinthefuturegrowthofthenearly900milliontonsofcoalminedinthecountrythatyear.Giventheuncertaintyinthefuturegrowthofnuclearpowerandinthesupplyofoilandnaturalgas,coal-firedpowerplantscouldwellprovideupto70percentoftheelectricpowerintheUnitedStatesbytheendofthecentury. Yet,inspiteofthefactthatcoalhaslongbeenasourceofelectricityandmayremainonformanyyears(coalrepresentsabout80percentofUnitedStatesfossil-fuelreserves),ithasactuallyneverbeenthemostdesirablefossilfuelforpowerplants.Coalcontainslessenergyperunitofweightthanweightthannaturalgasoroil;itisdifficulttotransport,anditisassociatedwithahostofenvironmentalissues,amongthemacidrain.Sincethelate1960sproblemsofemissioncontrolandwastedisposalhavesharplyreducedtheappealofcoal-firedpowerplants.Thecostofamelioratingtheseenvironmentproblemsalongwiththerisingcostofbuildingafacilityaslargeandcomplexasacoal-firedpowerplant,havealsomadesuchplantslessattractivefromapurelyeconomicperspective. Changesinthetechnologicalbaseofcoal-firedpowerplantscouldrestoretheirattractiveness,however.Whereassomeofthesechangesareintendedmainlytoincreasetheproductivityofexistingplants,completelynewtechnologiesforburningcoalcleanlyarealsobeingdeveloped. 10Americanblackbears Americanblackbearsappearinavarietyofcolorsdespitetheirname.Intheeasternpartoftheirrange,mostofthesebrown,red,orevenyellowcoats.Tothenorth,theblackbearisactuallygrayorwhiteincolor.Eveninthesamelitter,bothbrownandblackfurredbearsmaybeborn. BlackbearsarethesmallestofallAmericanbears,ranginginlengthfromfivetosixfeet,weighingfromthreehundredtofivehundredpoundsTheireyesandearsaresmallandtheireyesightandhearingarenotasgoodastheirsenseofsmell. Likeallbears,theblackbearistimid,clumsy,andrarelydangerous,butifattacked,mostcanclimbtreesandcovergroundatgreatspeeds.Whenangryorfrightened,itisaformidableenemy. Blackbearsfeedonleaves,herbs.Fruit,berries,insects,fish,andevenlargeranimals.Oneofthemostinterestingcharacteristicsofbears,includingtheblackbear,istheirwintersleep.Unlikesquirrels,woodchucks,andmanyotherwoodlandanimals,bearsdonotactuallyhibernate.Althoughthebeardoesnotduringthewintermoths,sustainingits