Arapidmeansoflong-distancetransportationbecameanecessityfortheUnitedStatesassettlement（新拓居地）spreadeverfartherwestward.Theearlytrainswereimpracticalcuriosities,andforalongtimetherailroadcompaniesmetwithtroublesomemechanicalproblems.Themostseriousonesweretheconstructionofrailsabletobeartheload,andthedevelopmentofasafe,effectivestoppingsystem.Oncetheseweresolved,therailroadwasestablishedasthebestmeansoflandtransportation.By1860therewerethousandsofmilesofrailroadscrossingtheeasternmountainrangesandreachingwestwardtotheMississippi.Therewerealsoregionalsouthernandwesternlines.
Thehighpointinrailroadbuildingcamewiththeconstructionofthefirsttranscontinentalsystem.In1862congressauthorizedtwowesternrailroadcompaniestobuildlinesfromNebraskawest-wardandfromCaliforniaeastwardtoameetingpoint,soastocompleteatranscontinentalcrossinglinkingtheAtlanticseaboardwiththePacific.TheGovernmenthelpedtherailroadsgenerouslywithmoneyandland
Actualworkonthisprojectbeganfouryearslater.Actualworkonthisprojectbeganfouryearslater.TheCentralPacificCompany,startingfromCalifornia,usedChineselabor,whiletheUnionPacificemployedcrewsofIrishlaborers.Thetwogroupsworkedatremarkablespeed,eachtryingto.coveragreaterdistancethantheother.Inl869theymetataplacecalledPromontoryinwhatisnowthestateofUtah.Manyvisitorscamethereforthegreatoccasion.Therewerejoyouscelebrationsallthecountry,withparadesandtheringingofchurchbellstohonorthegreatachievement.
Therailroadwasveryimportantinencouragingwestwardmovement.Italsohelpedbuildupindustryandfarmingbymovingrawmaterialsandbydistributingproductsrapidlytodistantmarkets.InlinkingtownsandpeopletooneanotherithelpedunifytheUnitedStates.
Thebesttitleforthispassagewouldbe__________.
A）SettlementsSpreadWestward
B）TheCoast-to-CoastRailroad:AVitalLink
C）AmericanRailroadHistory
D）TheImportanceofTrainsintheAmericanEconomy
本题是给文章选标题,实际上也是问及全篇的主旨。文章第一段的第一句虽然提到"settlementspreadeverfartherwestward",但这不是本文论述的中心,太故选项A）是错的；选项D）也不合适,因为作者在第三段第二句里谈的是在美国起重要作用的transcontinentalrailway,而不是泛指美国的铁路；虽然本文从一个侧面反映了美国铁路的历史,故选项C）也是错的；本文的第三段点了文章的主旨,即这条横贯美国的铁路在开发西部、发展工农业生产和统一美国等方面起到了avitallink的作用。因此,答案应该是选项B）
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