阅读理解

Beforethemid-nineteenthcenturypeopleintheUnitedStatesatemostfoodsonlyinseason.Dryingsmokingandsaltingcouldkeepmeatforashorttimebutthechanceofeatingfreshmeatanddrinkingfreshmilkwasverylimited:therewasnowaytokeepfoodfromgoingbad.Butin1810aFrenchinventornamedNicolasAppertdevelopedthecooking-and-sealingtechniqueofcanning.Andinthe1850'sanAmericannamedGailBordendevelopedameansofkeepingmilkfresh.Cannedfoodsandcondensedmilk(炼乳)becamemorecommonduringthe1860'sbutsuppliesremainedlowbecausecanshadtobemadebyhand.By1880howeverinventorshaddevelopedmodernmachinesthatmass-producedcansfromtin-plate.Suddenlyallkindsoffoodcouldbekeptandboughtatalltimesoftheyear.

OtherinventionshadalsohelpedmakeitpossibleforAmericanstochangetheirdailydiets.Growingpopulationsincreasedfooddemandandstimulatedfruitandvegetablefarmerstoraisemoreproduce.Railroadrefrigeratorcarsmadeitpossibletoshipgrowersandpackedmeatfreshtofarawayplaceswithoutworryingtheywouldgobad.Thusbythe1890'snortherncitysettlerscouldenjoysouthernandwesternstrawberriesgrapesandtomatoesforamonthatmostinthepastforuptosixmonthsoftheyear.Besidesincreaseduseoficeboxesmadeitpossibleforfamiliestostorefoodwhichcouldeasilygobad.Aneasymeansofproducingicehadbeeninventedinthe1870'sandby1900thenationhadmorethantwothousandiceplantsmostofwhichmadehomedeliveries.Theiceboxbecamecommonequipmentinmosthomesandremainedsountiltherefrigeratorreplaceditinthe1920'sand1930's.Almosteveryonenowhasavarietyofdiet.

1．Whatdoesthepassagemainlydiscuss?

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A．Causesoffoodgoingbad.

B．Productionoficeboxes.

C．Inventionsthatledtochangesinfoodanddrink.

D．Cannedfood.

2．Theunderlinedword“stimulate”means________.

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A．protect

B．encourage

C．enable

D．persuade

3．Thewritersuggestedthatinthe1920'sand1930'shomedeliveriesofice________.

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A．reducedinnumber

B．becameverycommon

C．increasedincost

D．