业务题Integrated Writing 　　Reading：Physicist Fred Hoyle casts doubt on the validness of the fossil of archaeopteryx, an ancient bird vital to the evolution from reptile to modern birds. He thinks that the fossil is faked by putting features of a modern bird into a layer of a limestone. The reasons he gives are 　　1）The fossil is discovered soon after the publication of Darwin’s theory of evolution; 　　2） The fossil is too perfectly preserved to be true; 　　3）When the limestone in which the fossil is stored in is cut in half, the two halves do not fit perfectly. 　　Listening: The professor completely refutes Hoyle’s theory. The reasons are: 　　1）The museum rejected the theory of evolution at first. This means the fossil could not be faked since even the museum did not approve it. 　　2） The limestone in which the fossil is stored in is very smooth, so it is reasonable that the details are well preserved 　　3） Scientists intentional removed some parts of the limestone, making it easier expose the bird’s tail.

业务题You have the opportunity to visit a foreign country for two weeks.Which country would you like to visit?Use specific reasons and details to explain your choice.

EnergyfromNaturalGas1.Muchoftheworldgetsitsenergyfromfossilfuelsources,includingcoal,oil,andnaturalgas,allofwhichwerecreatedmillionsofyearsago.Theprocessbeganwithdeadplantandanimalmatterthatcollectedandovertimewasburieddeepwithintheearth.There,exposedtoextremepressureandtemperatures,thecarbon-basedmaterialunderwentvariouschemicalandphysicalchanges.Someofitbecamecoal,someoil,andsomenaturalgas,dependingontheexactconditionsitwassubjectedto.2.Naturalgasisbothinvisibleandodorless.Duringthefirstcenturyofthefossilfuelera,itwasdisregardedasaworthlessbyproductofcoalandoil.However,peoplelaterdiscoveredthatitcouldalsobeausefulsourceofenergy,andtheysetabouttryingtorealizeitspotential.Itsusebegantogrowinthetwentiethcenturyandhasincreasedrapidlywithinthelast40years.Nowadays,naturalgasisemployedallovertheworldtoheathomes,generateelectricity,powerfactories,andevenfuelvehicles.3.Becauseitwascreatedthroughthesameprocessasotherfossilfuels,naturalgascanoftenberetrievedfromoilfields,somethingknownasanassociatedsource.Coalbedshavesimilarlybeenknowntoyieldnaturalgas.Inaddition,thereareisolateddepositscontainingonlygasthatarereferredtoasnon-associatedsources.Toaccessasubterraneannaturalgaspocket,aholeisdrilleddownintoit,justasinoilextraction.However,duetothegas'slightness,itwillrisetothesurfaceonitsowninsteadofhavingtobepumpedout.4.Thecompoundweknowasnaturalgasisactuallyacompositeofseveraldifferentsubstances,theprimaryonebeingmethanegas.Eachdeposithasauniquemakeup,butothercommoncomponentsofnaturalgasincludepropane,butane,andsulfur.Borrowingtermsusedinthedescriptionofoil,naturalgaswithahighsulfurcontentiscalled"sour"whilethatwithalowcontentisreferredtoas"sweet"Regardlessoftheexactcomposition,naturalgasmustberefinedtoremoveitsimpurities;whenreadyforuse,itisnearlypuremethane.5.Naturalgasoffersmanyadvantagesasafuelsource,thefirstandmostimportantbeingthatitisextremelycleanburning.Whileoilandcoalbothhavecomplexmolecularstructures,methane'sissimple:onecarbonatomsurroundedbyfouratomsofhydrogen.Thelackofexcessparticlestranslatesintofewerwastebyproductsduringcombustion.Forexample,allfossilfuelsproducecarbondioxidewhenburned,butnaturalgasreleasessubstantiallylesscarbondioxidethanotherfuels.Giventhemajorroleofcarbondioxideintheaccelerationofglobalwarming,thisisanimportantattribute.Inaddition,naturalgasemitsfarlessnitrogenandsulfur,whicharekeycontributorstothesmogthatpollutestheairinmetropolitanareas,aswellasacidrain.6.Thebenefitsofnaturalgasextendfarbeyonditscleanliness.Sinceitcontainsfewerwasteparticles,itsenergycanbeacquiredwithmuchmoreefficiencythanthatoftheotherfossilfuels,meaningaloweroverallcostfortheconsumer.Anotheradvantageisthatnaturalgasistransportedviaundergroundpipelinesinsteadofbyshipsandtrucks.Finally,naturalgasisrelativelyplentifulandwidespread.GeologistshaveidentifiedextensivestoresinCanada,theUnitedStates,Russia,theMiddleEast,andAustralia,amongotherlocations.Withtheworld'soilsuppliesquicklydwindling,itisbecomingmoreimportantthanevertoutilizealternativeenergyresourcessuchasnaturalgas.7.Ofcourse,noenergyresourceisperfect,andtherearesomedrawbackstotheuseofnaturalgas.Itslowdensitymeansthatitrequireslargertanksforstoragethanoilandcoaldo,anditisimpossibletopipeitacrosstheoceans.Somepeoplehaveconcernsaboutitssafetyaswell,sinceitslackofcolorandsmellcanmakedetectingaleakdifficult.However,whenbothitspositiveandnegativecharacteristicsareweighed,itbecomesclearthatnaturalgasisperhapsthebestenergyresourceavailabletoday.

1 Although some fish appear capable of swimming at extremely high speeds, most fish, such as trout and minnows, can actually swim only about ten body lengths per second. Translated into kilometers per hour, it means that a 30-centimeter trout can swim only about 10.4 kilometers per hour. Generally speaking, the larger the fish the faster it can swim. 2 We can understand how fish swim by studying the motion of a very flexible fish such as an eel. The movement is serpentine, with undulations moving backward along the body by alternate contraction of the muscles on either side of the eel's body. While the undulations move backward, the bending of the body pushes sideways against the water, producing a reactive force that is directed forward at an angle. The movement has two components: thrust and lateral force. Thrust is used to propel the fish forward, and lateral force tends to make the fish's head deviate from the course in the same direction as the tail. This side-to-side head movement is very obvious in a swimming eel, but fish with large, rigid heads have enough surface resistance to minimize the lateral movement.

CLOTHING AND COSTUME 1 The ancient Greeks and the Chinese believed that we first clothed our bodies for some physical reason, such as protecting ourselves from the elements. Ethnologists and psychologists have invoked psychological reasons: modesty, taboo, magical influence, or the desire to please. Anthropological research indicates that the function of the earliest clothing was to carry objects. Our hunting-gathering ancestors had to travel great distances to obtain food. For the male hunters, carrying was much easier if they were wearing simple belts or animal skins from which they could hang weapons and tools. For the female gatherers, more elaborate carrying devices were necessary. Women had to transport collected food back to the settlement and also had to carry babies, so they required bags or slings. 2 Another function of early clothing--providing comfort and protection--probably developed at the same time as utility. As human beings multiplied and spread out from the warm lands in which they evolved, they covered their bodies more and more to maintain body warmth. Today, we still dress to maintain warmth and to carry objects in our clothes. And like our hunting-gathering ancestors, most men still carry things on their person, as if they still needed to keep their arms free for hunting, while women tend to have a separate bag for carrying, as if they were still food-gatherers. But these two functions of clothing are only two of many uses to which we put the garments that we wear today. 3 There is a clear distinction between attire that constitutes "clothing" and attire that is more aptly termed "costume." We might say that clothing has to do with covering the body, and costume concerns the choice of a particular form of garment for a particular purpose. Clothing depends primarily on such physical conditions as climate, health, and textile, while costume reflects social factors such as personal status, religious beliefs, aesthetics, and the wish to be distinguished from or to emulate others. 4 Even in early human history, costume fulfilled a function beyond that of simple utility. Costume helped to impose authority or inspire fear. A chieftain"s costume embodied attributes expressing his power, while a warrior"s costume enhanced his physical superiority and suggested he was superhuman. Costume often had a magical significance such as investing humans with the attributes of other creatures through the addition of ornaments to identify the wearer with animals, gods, or heroes. In more recent times, professional or administrative costume is designed to distinguish the wearer and to express personal or delegated authority. Costume communicates the status of the wearer, and with very few exceptions, the aim is to display as high a status as possible. Costume denotes power, and since power is often equated with wealth, costume has come to be an expression of social class and material prosperity. 5 A uniform is a type of costume that serves the important function of displaying membership in a group: school, sports team, occupation, or armed force. Military uniform denotes rank and is intended not only to express group membership but also to protect the body and to intimidate. A soldier"s uniform says, "I am part of a powerful machine, and when you deal with me, you deal with my whole organization." Uniforms are immediate beacons of power and authority. If a person needs to display power--a police officer, for example--then the body can be virtually transformed. Height can be exaggerated with protective headgear, thick clothing can make the body look broader and stronger, and boots can enhance the power of the legs. Uniforms also convey low social status; at the bottom of the scale, the uniform of the prisoner denotes membership in the society of convicted criminals. Religious costume signifies spiritual or superhuman authority and possesses a significance that identifies the wearer with a belief or god. A successful clergy has always displayed impressive vestments of one kind or another that clearly demonstrate the religious leader"s dominant status.

Reading2"Civilization"Between4000and3000B.C.,significanttechnologicaldevelopmentsbegantotransformtheNeolithictowns.Theinventionofwritingenabledrecordstobekept,andtheuseofmetalsmarkedanewlevelofhumancontrolovertheenvironmentanditsresources.Alreadybefore4000B.C.,craftspeoplehaddiscoveredthatmetal-bearingrockscouldbeheatedtoliquefymetals,whichcouldthenbecastinmoldstoproducetoolsandweaponsthatweremoreusefulthanstoneinstruments.Althoughcopperwasthefirstmetaltobeutilizedinproducingtools,after4000B.C.craftspeopleinwesternAsiadiscoveredthatacombinationofcopperandtinproducedbronze,amuchharderandmoredurablemetalthancopper.ItswidespreadusehasledhistorianstospeakofaBronzeAgefromaround3000to1200B.C.,whenbronzewasincreasinglyreplacedbyiron.→Atfirst,Neolithicsettlementswerehardlymorethanvillages.Butastheirinhabitantsmasteredtheartoffarming,theygraduallybegantogivebirthtomorecomplexhumansocieties.Aswealthincreased,suchsocietiesbegantodeveloparmiesandtobuildwalledcities.BythebeginningoftheBronzeAge,theconcentrationoflargernumbersofpeopleintherivervalleysofMesopotamiaandEgyptwasleadingtoawholenewpatternforhumanlife.→Aswehaveseen,earlyhumanbeingsformedsmallgroupsthatdevelopedasimpleculturethatenabledthemtosurvive.Ashumansocietiesgrewanddevelopedgreatercomplexity,anewformofhumanexistence—calledcivilization-cameintobeing.Acivilizationisacomplexcultureinwhichlargenumbersofhumanbeingsshareanumberofcommonelements.{{U}}Historianshave{{/U}}{{U}}identifiedanumberofbasccharacterstcsofcivilization,mostofwhichare{{/U}}{{U}}evidentintheMesopotamianandEgyptiancivilizations.{{/U}}Theseinclude(1)anurbanrevolution;citiesbecamethefocalpointsforpolitical,economic,social,cultural,andreligiousdevelopment;(2)adistinctreligiousstructure;thegodsweredeemedcrucialtothecommunity'ssuccess,andprofessionalpriestlyclasses,asstewardsofthegods'property,regulatedrelationswiththegods;(3)newpoliticalandmilitarystructures;anorganizedgovernmentbureaucracyarosetomeettheadministrativedemandsofthegrowingpopulationwhilearmieswereorganizedtogainlandandpower;(4)anewsocialstructurebasedoneconomicpower;whilekingsandanupperclassofpriests,politicalleaders,andwarriorsdominated,therealsoexistedlargegroupsoffreepeople(farmers,artisans,craftspeople)andattheverybottom,socially,aclassofslaves;(5)thedevelopmentofwriting;kings,priests,merchants,andartisansusedwritingtokeeprecords;and(6)newformsofsignificantartisticandintellectualactivity,suchasmonumentalarchitecturalstructures,usuallyreligious,occu-pieda{{U}}prominent{{/U}}placeinurbanenvironments.→Whyearlycivilizationsdevelopedremainsdifficulttoexplain.SincecivilizationsdevelopedindependentlyinIndia,China,Mesopotamia,andEgypt,cangeneralcausesbeidentifiedthatwouldexplainwhyallofthesecivilizationsemerged?Anumberofpossibleexplanationsofthebeginningofcivilizationhavebeensuggested.Atheoryofchallengeandresponsemaintainsthatchallengesforcedhumanbeingstomakeeffortsthatresultedintheriseofcivilization.Somescholarshaveadheredtoamaterialexplanation.[]Materialforces,suchasthegrowthoffoodsurpluses,madepossiblethespecializationoflaboranddevelopmentoflargecommunitieswithbureaucraticorganization.ButtheareaoftheFertileCrescent,inwhichMesopotamiancivilizationemerged,wasnotnaturallyconducivetoagriculture.Abundantfoodcouldonlybeproducedwithamassivehumanefforttocarefullymanagethewater,aneffortthatcreatedtheneedfororganizationandbureaucraticcontrolandledtocivilizedcities.Somehistorianshavearguedthatnonmaterialforces,primarilyreligious,providedthesenseofunityandpurposethatmadesuchorganizedactivitiespossible.Finally,somescholarsdoubtthatwearecapableofeverdiscoveringtheactualcausesofearlycivilization.

IodineandGoiterIodineisawell-knownexampleofatracemineralwhoselackinthebodycreatesaneasilytreateddisease.Whenthethyroidglandisnotsuppliedwithsufficientiodinetomanufacturehormones,itenlargesandformsagoiterorswellingoftheneck.Atthesametimeothersymptoms,suchasfatigueandsluggishness,weightgain,coldnessofthebody,anddepression,mayoccur.IntheUnitedStatesgoiterwasfirstnotedintheGreatLakesregion,whereinthe1930s,asmanyas40percentofthepeopleinsomeareashadgoiter,duemainlytoiodine-deficientsoil.Thisscarcityhadbeencausedbyiceageglaciersmeltingandwashingtheiodineoutofthesoil.TheinhabitantsofmountainousregionsofEuropehadsufferedfromiodinedeficiencyforcenturiesforsimilarreasons.ItwasdiscoveredinthealpineregionofSwitzerlandinthenineteenthcenturythatinareasinwhichthedrinkingwatercontainedlessthan0.5microgramsofiodineperlitertherewasahighincidenceofgoiter.Incontrasttomountainousorinlandregions,areasbyoceansorinthevicinityofoceanbreezesusuallycontainenoughiodinetopreventthisaffliction.Asafairlyaccurateruleofthumb,ifamapisdrawnshowingthepartsoftheworldwherethewatersupplyisdeficientiniodineandthensuperimposedonamapshowingtheareaswheretheinhabitantssufferfromgoiter,thetwomappedareascoincide.Tounderstandhowiodinedeficiencyleadstogoiter,itisnecessarytolookattheunderlyingphysiologyofthethyroidgland.Thehumanthyroidglandistheonlyplaceinthebodywhereiodineisstored,anditrequiresadailysupplyofabout150microgramsofiodineenteringthebody.Whenfoodorwaterisdigested,theiodineitcontainsiseithertakenupbythethyroidoreliminatedfromthebodythroughthekidneysintotheurine.Whensuppliesarelow,thekidneysstilleliminateiodinefromthebodysothecapacityofthethyroidtopreserveanadequatesupplyofrawmaterialisthreatened.Thethyroidglandconsistsofthousandsofballsofcells,calledthyroidvesicles,whichencloseaspacefilledwithajellylikeproteincalledthyroglobulin.Thesecellshaveanextraordinaryabilitytotrapiodinefromthebloodstream,andtheefficiencyofthistrapcanbeincreasediftheamountofiodineinthebloodcirculationdecreases.Oncetheiodineistrappedbythethyroidvesiclesitpassesintothethyroglobulin,wheretheactualmanufactureoftwokindsofthyroidhormonestakesplace.Thehormonesarestoredhereuntiltheytravelbackthroughthethyroidvesiclestoenterthebloodstream.Thethyroidhormonesarethentakentoeverypartofthebodywheretheyinfluencetherateatwhichthechemicalprocessesofeverycellproceed.Theyhaveapervasiveeffectonthecontrolofoxygenconsumptionandheatproductionofthewholebody,andtheyareessentialtothehealthygrowthofbodyandmind.Thethyroidtriestokeepconstanttheamountofcirculatingthyroidhormoneenteringthecellsofthebody.Wheniodinesuppliesarelow,thepituitarygland,asmallpea-sizedglandatthebaseofthebrain,secretesathyroid-stimulatinghormone(TSH)thatinturnregulatesthepowerofthethyroidtotrapiodineandincreasetheoutputofthethyroid.IfthethyroidiscontinuallystimulatedbyTSH,thecellsgetlargerandeventuallythewholeglandenlargeswithanincreaseinthenumberofitscells.ThethyroidmayhavemanytemporarycriseswhereiodinesuppliesarenotadequateandwhereswellingininducedundertheinfluenceofTSH.Aseriesofsuchincidentsoveralongperiodoftimewilleventuallycausealargethyroidswellingsincetheglanddoesnotalwaysresumeitsprevioussizeandshape.Glossary:superimposed:oneimagepositionedoveranothersothatbothimagescanbeseentogetherpervasive:spreadingthroughallparts

Directions : Read the passage

TOEFLReadingPassage1TheSnake'sForkedTongue1.Oneofthemostintriguingphysicalcharacteristicsofsnakesistheirforkedtongues.Whilethistraitisalsosharedbysometypesoflizards,allsnakespeciesexhibitsplittongues,whichusuallyhaveamorepronouncedforkthanthoseoflizards.Anyobserverofsnakeshasnodoubtnoticedthattheyoftensticktheirtonguesoutoftheirmouths,flickthemupanddownintheair,andthenretractthem.Infact,duetoaslightindentationintheupperjaw,manyspeciescanprotrudetheirtongueswithoutevenopeningtheirmouths.2.Theexplanationforthisbehaviorremainedunknownforcenturies,givingrisetomanyfolksuperstitions.Forexample,theforkedtonguehasbecomesynonymouswithdeceit,fromtheideathattwoseparatetongueswouldenableacreaturetovoicetwocontrastingideasatthesametime.Anotherpopularmisconceptionisthatsnakesstingotheranimalswiththeirtongues.Recently,though,scientistsuncoveredthetruthabouttheforkedtongue,anditsactualuseismuchlesssinister.3.Snakesdiffergreatlyfromhumansonasensorylevel.Ontheonehand,theireyesightispoorandtheylackouterearssotheycannothearwithmuchvolumeorclarity,but,ontheother,somehavetheabilityto"see"andhuntinthedarkbysensingthebodyheatoftheirprey.Inaddition,snakeshaveamethodofsmellingthatispeculiarinthatitisactuallyperformedbythetongueratherthanbythenostrilsandnasalcavities,whichinfactundertakeotherfunctions,suchasbreathing.Whenasnakeflicksitstonguearoundintheair,itisactuallysnaringchemicalparticles,whichcanbethoughtofasodors.Next,thesnakebringsitstonguebackinandplacesitagainsttheroofofitsmouth,wheretherearetwosmallopeningsthatcorrespondtothetwotipsoftheforkedtongue.Thesemakeupthesnake'sJacobson'sorgan,akindofchemoreceptorthatanalyzesthechemicalodorsonthetongueandsendsthisinformationtothesnake'sbrain.4.Thistechniquefor"smelling"thesurroundingenvironmentistrulyunique,butevenmoreamazingisthereasonwhythesnake'stongueisforked.Byspreadingthetipsapartwhenthetongueisflickedout,eachsampleschemicalparticlesfromaslightlydifferentpositionintheairandbringsthembacktotheJacobson'sorgan.Theorganthendetermineswhichtipwasexposedtoalargeramountoftheparticlesinquestion,andthisdatatellsthesnakewherethesourceoftheodorcanbefound.Inotherwords,ifthetongue'srighttipcontainsmoreoftheparticles,suchasthoseofananimal'schemicalodor,thesnakeknowsthattofindtheanimalitmusttraveltotheright,nottotheleft.5.Obviously,theabilityofsnakestopursuescentsinthisfashionisveryusefulinhunting,Ithasbeenproventobequiteaccurate,allowingthemtopickupthetrailofrodentsandotherpreyeventhoughtheanimalitselfmaybeagreatdistanceaway.Similarly,iftheodorthesnakeperceivesbelongstoapredator,itisabletoadjustitscoursetosteerclearofthedanger,Anothersuggesteduseofsnakes'senseofsmellisthatitaidstheminascertainingthelocationsofcommunaldens*,wheresnakesresideingroupsduringthewintermonths.6.However,scientistswhohavestudiedthechemoreceptionprocessinsnakesbelieveitsmostvitalroleisinthedetectionofmates.Becausemostsnakesleadsolitarylivesformuchoftheyear,thecapabilityofmalestotrackdownfemalesduringthematingseasonisessentialforthesurvivalofsnakespecies.Amaledoesthisbysamplingtheairforthepheromonesofafemale.Thechemicalodorgivenoffbythefemalegivesthemalealltheinformationheneeds,includingwhethersheisofthesamespecies,whethersheisreadytomate,andinwhichdirectionsheistraveling.Withouttheolfactoryuseoftheirtongues,itwouldbemuchharderforsnakestoreproduce.den*thehomeofcertaintypesofwildanimalssuchaslionsorfoxes

Listentopartofalectureinatechnologyclass.Nowgetreadytoanswerthequestions.Youmayuseyournotestohelpyouanswer.

Nineteenth-CenturyPoliticsintheUnitedStatesThedevelopmentofthemodempresidencyintheUnitedStatesbeganwithAndrewJacksonwhoswepttopowerin1829attheheadoftheDemocraticPartyandserveduntil1837.Duringhisadministrationheimmeasurablyenlargedthepowerofthepresidency."ThePresidentisthedirectrepresentativeoftheAmericanpeople,"helecturedtheSenatewhenitopposedhim."Hewaselectedbythepeople,andisresponsibletothem."Withthisdeclaration,Jacksonredefinedthecharacterofthepresidentialofficeanditsrelationshiptothepeople.DuringJackson'ssecondterm,hisopponentshadgraduallycometogethertoformtheWhigparty.WhigsandDemocratshelddifferentattitudestowardthechangesbroughtaboutbythemarket,banks,andcommerce.TheDemocratstendedtoviewsocietyasacontinuingconflictbetween"thepeople"--farmers,planters,andworkers--andasetofgreedyaristocrats.This"papermoneyaristocracy"ofbankersandinvestorsmanipulatedthebankingsystemfortheirownprofit,Democratsclaimed,andsappedthenation'svirtuebyencouragingspeculationandthedesireforsudden,unearnedwealth.TheDemocratswantedtherewardsofthemarketwithoutsacrificingthefeaturesofasimpleagrarianrepublic.Theywantedthewealththatthemarketofferedwithoutthecompetitive,changingsociety;thecomplexdealing;thedominanceofurbancenters;andthelossofindependencethatcamewithit.Whigs,ontheotherhand,weremorecomfortablewiththemarket.Forthem,commerceandeconomicdevelopmentwereagentsofcivilization.NordidtheWhigsenvisionanyconflictinsocietybetweenfarmersandworkersontheonehandandbusinesspeopleandbankersontheother.Economicgrowthwouldbenefiteveryonebyraisingnationalincomeandexpandingopportunity.Thegovernment'sresponsibilitywastoprovideawell--regulatedeconomythatguaranteedopportunityforcitizensofability.WhigsandDemocratsdifferednotonlyintheirattitudestowardthemarketbutalsoabouthowactivethecentralgovernmentshouldbeinpeople'slives.DespiteAndrewJackson'sinclinationtobeastrongPresident,Democratsasarulebelievedinlimitedgovernment.Government'sroleintheeconomywastopromotecompetitionbydestroyingmonopoliesandspecialprivileges.Inkeepingwiththisphilosophyoflimitedgovernment,Democratsalsorejectedtheideathatmoralbeliefswerethepropersphereofgovernmentaction.Religionandpolitics,theybelieved,shouldbekeptclearlyseparate,andtheygenerallyopposedhumanitarianlegislation.TheWhigs,incontrast,viewedgovernmentpowerpositively.Theybelievedthatitshouldbeusedtoprotectindividualrightsandpublicliberty,andthatithadaspecialrolewhereindividualeffortwasin-effective.Byregulatingtheeconomyandcompetition,thegovernmentcouldensureequalopportunity.Indeed,forWhigstheconceptofgovernmentpromotingthegeneralwelfarewentbeyondtheeconomy.Inparticular,WhigsinthenorthernsectionsoftheUnitedStatesalsobelievedthatgovernmentpowershouldbeusedtofosterthemoralwelfareofthecountry.Theyweremuchmorelikelytofavorsocialreformlegislationandaidtoeducation.Insomewaysthesocialmakeupofthetwopartieswassimilar.Tobecompetitiveinwinningvotes,WhigsandDemocratsbothhadtohavesignificantsupportamongfarmers,thelargestgroupinsociety,andworkers.Neitherpartycouldwinanelectionbyappealingexclusivelytotherichorthepoor.TheWhigs,however,enjoyeddisproportionatestrengthamongthebusinessandcornmercialclasses.Whigsappealedtoplanterswhoneededcredittofinancetheircottonandricetradeintheworldmarket,tofarmerswhowereeagertoselltheirsurpluses,andtoworkerswhoIwishedtoimprovethemselves.Democratsattractedfarmersisolatedfromthemarketoruncomfortablewithit,workersalienatedfromtheemergingindustrialsystem,andrisingentrepreneurswhowantedtobreakmonopoliesandopentheeconomytonewcomerslikethemselves.TheWhigswerestrongestinthetowns,cities,andthoseruralareasthatwerefullyintegratedintothemarketeconomy,whereasDemocratsdominatedareasofsemi-subsistencefarmingthatweremoreisolatedandlanguishingeconomically.

BiologicalBarriersandPathwaysVirtuallyalllivingthingshavesomewayofgettingfromheretothere.Animalsmaywalk,swim,orfly.Plantsandtheirseedsdriftonwindorwaterorarecarriedbyanimals.Therefore,itisreasonabletoexpectthat,intime,allspeciesmightspreadtoeveryplaceonEarthwherefavorableconditionsoccur.Indeed,therearesomecosmopolitanspecies.Agoodexampleisthehousefly,foundalmosteverywhereonEarth.However,suchbroaddistributionistherareexception.Justasbarbedwirefencespreventcattlefromleavingtheirpasture,biologicalbarrierspreventthedispersalofmanyspecies.Whatconstitutesbarriersdependsonthespeciesanditsmethodofdispersal.Somearephysicalbarriers.Forlandanimals,bodiesofwater,chainsofmountains,ordesertsareeffective.Forexample,theAmericanbisonspreadthroughouttheopengrasslandsofNorthAmerica,butinthesouthernpartofthecontinenttherearedeserts,sothebisoncouldnotspreadthere.Foraquaticcreatures,strongcurrents,differencesinsalinity,orlandareasmayserveasbarriers.Somebarriersinvolvecompetitionwithotherspecies.Adandelionseedmaybecarriedbythewindtobareground,and,ifenvironmentalfactorsareright,itmaygerminate.Thereisnotmuchchance,however,thatanyindividualseedlingwillsurvive.Mostplacesthataresuitableforthegrowthofdandelionsarealreadyoccupiedbyothertypesofplantsthatarewelladaptedtothearea.Thedandelionseedlingmustcompetewiththeseplantsforspace,water,light,andnutrients.Facingsuchstiffcompetition,thechancesofsurvivalareslim.Foranimals,somebarriersarebehavioral,ThebluespottedsalamanderlivesonlyonmountainslopesinthesouthernAppalachianHighlands.Althoughthesecreaturescouldsurviveintherivervalleys,theyneverventurethere.Birdsthatflylongdistancesoftenremaininverylimitedareas.Kirkland'swarblersarefoundonlyinafewplacesinMichiganinthesummerandflytotheBahamasinwinter.Nophysicalbarriersrestrictthewarblerstothesetwolocations,yettheyneverspreadbeyondtheseboundaries.Brazil'sAmazonRiverservesasanorthernorsouthernboundaryformanyspeciesofbirds.Theycouldfreelyflyovertheriver,buttheyseldomdo.Therearethreetypesofnaturalpathwaysthroughwhichorganismscanovercomebarriers.Onetypeiscalledacorridor.Acorridorconsistsofasingletypeofhabitatthatpassesthroughvariousothertypesofhabitat.NorthAmerica'sRockyMountains,whichstretchfromAlaskatonorthernMexico,isanexample.Varioustypesoftrees,suchastheEngehnannspruce,canbefoundnotonlyatthenorthernendofthecorridorinAlaskabutalsoathigherelevationsalongtheentirelengthofthiscorridor.Asecondtypeofnaturalpathwayisknownasafilterroute.Afilterrouteconsistsofaseriesofhabitatsthataredifferentfromoneanotherbutaresimilarenoughtopermitorganismstograduallyadapttonewconditionsastheyspreadfromhabitattohabitat.Thegreatestdifferencebetweenacorridorandafilterrouteisthatacorridorconsistsofonetypeofhabitat,whileafilterconsistsofseveralsimilartypes.Thethirdtypeofnaturalpathwayiscalledasweepstakesroute.Thisisdispersalcausedbythechancecombinationoffavorableconditions.Birdwatchersarefamiliarwith"accidentals",whicharebirdsthatappearinplacesfarfromtheirnativeareas.Sometimestheymayfindahabitatwithfavorableconditionsand"colonize"it.Gardenersarefamiliarwith"volunteers",cultivatedplantsthatgrowintheirgardensalthoughtheyneverplantedtheseedsfortheseplants.Besidesbirdsandplants,insects,fish,andmammalsalsocolonizenewareas.Sweepstakesroutesareunlikeeithercorridorsorfilterroutesinthatorganismsthattraveltheserouteswouldnotbeabletospendtheirentirelivesinthehabitatsthattheypassthrough.Someorganismscrossbarrierswiththeintentionalorunintentionalhelpofhumans,aprocesscalledinvasion.AnexampleistheNewZealandmudsnail,whichwasaccidentallybroughttoNorthAmericawhentroutfromNewZealandwereimportedtoafishhatcheryintheUnitedStates.Ithascausedextensiveenvironmentaldamageinstreamsandrivers.Intheinvasivespecies'nativeenvironments,therearetypicallypredators,parasites,andcompetitorsthatkeeptheirnumbersdown,butintheirnewhabitat,naturalchecksareleftbehind,givingtheinvadersanadvantageovernativespecies.Invasivespeciesmayspreadsoquicklythattheythreatencommercial,agricultural,orrecreationalactivities.Glossarysalamander:atypeofamphibiananimalresemblingalizardsweepstakes:agameofchance;alottery