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1、考研英语阅读理解思路透析和真题揭秘(56)Passage4 Emergingfromthe1980censusisthepictureofanationdevelopingmoreandmoreregionalpetition,aspopulationgroent-anditsstrongimplicationsforUSpoliticsandeconomyinyearsahead-hasenthronedtheSouthasAmerica'smostdenselypopulatedregionforthefirsttime
2、inthehistoryofthenation'sheadcounting. Altogether,theUSpopulationroseinthe1970sby23.2millionpeople-numericallythethirdlargestgroericanannualrecordsexceptfortheDepressionyears. Americanshavebeenmigratingsouthandbersinceoreover,demographersseethecontinuingshiftsouth
3、andenon:Moreandmore,Americansapparentlyarelookingnotjustforplacesorejobsbuteinstances- ●Regionally,theRockyMountainstatesreportedthemostrapidgroongstates,NevadaandArizonagreillionpeople-about9persquaremile. Theflightfromovercroigrationfromsnoorebearableclimates.
4、NoatizemoretheAmericansearchforspaciouslivingthanintheFarilliontoitspopulationinthe1970s,morethananyotherstate. Inthatdecade,hobersalsomigratedfromCalifornia,mostlytootherpartsoftheeatessuchasOregon,IdahoandAlaskainordertoescapesmog,crimeandotherplaguesofurbanizati
5、onintheGoldenState. Asaresult,California'sgroorethanttheperplexingpictureofpopulationgroericain1970s_____. [A]enjoyedthelowestgrowthofpopulationinhistory [B]igrationsinceostofthehotspotsmoveonlysloecasesthemovementoftheplatespastthemhaslefttrailsofdeadvolcanoes.T
6、hehotspotsandtheirvolcanictrailsaremilestonesthatmarkthepassageoftheplates. Thattheplatesaremovingisnotbeyonddispute.AfricaandSouthAmerica,forexample,aremovingaeachotherasneaterialisinjectedintotheseafloorbet.Theplementarycoastlinesandcertaingeologicalfeaturesthats
7、eemtospantheoceanareremindersofotionoftheplatescarryingthesecontinentshasbeenconstructedindetail,butthemotionofoneplateotionineovinginoppositedirectionsorit.Hotspots,anchoredinthedeeperlayersoftheearth,providethemeasuringinstrumentsneededtoresolvethequestion.Fromana
8、nalysisofthehotspotpopulationitappearsthattheAfricanplateisstationaryandthatithasnotmovedduringthepast30millionyears. Thesignificanceofho
