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1、托福备考-TOFEL试题8TOFEL试题8月托福阅读试题Questions:1-10Aseventeenth-centurytheoryofburningproposedthatanythingthatburnsmustcontainmaterialthatthetheoristscalled"phlogiston."Burningwasexplainedasthereleaseofphlogistonfromthecombustiblematerialtotheair.Airwasthoughtessential,sinceithadtoprovideahomeforthereleased
2、phlogiston.Therewouldbealimittothephlogistontransfer,sinceagivenvolumeofaircouldabsorbonlysomuchphlogiston.Whentheairhadbecomesaturated,noadditionalamountsofphlogistoncouldleavethecombustiblesubstance,andtheburningwouldstop.Burningwouldalsostopwhenthecombustiblesubstancewasemptiedofallitsphlogiston
3、.Althoughthephlogistontheorywasself-consistent,itwasawkwardbecauseitrequiredthatimaginative,evenmysterious,propertiesbeascribedtophlogiston.Phlogistonwaselusive.Noonehadeverisolateditandexperimentallydetermineditsproperties.Attimesitseemedtoshowanegativeweight:theresidueleftafterburningweighedmoret
4、hanthematerialbeforeburning.Thiswastrue,forexample,whenmagnesiumburned.Sometimesphlogistonseemedtoshowapositiveweight,when,forexample,woodburned,theashweighedlessthanthestartingmaterial.Andsincesolittleresiduewasleftwhenalcohol,kerosene,orhigh-gradecoalburned,theseobviouslydifferentmaterialsweretho
5、ughttobepureornearlypurephlogiston.Intheeighteenthcentury,AntoineLavoisier,onthebasisofcarefulexperimentation,wasledtoproposeadifferenttheoryofburning,onethatrequiredaconstituentofair-latershowntobeoxygen-forcombustion.Sincetheweightoftheoxygenisalwaysadded,theweightoftheproductsofcombustion,includ
6、ingtheevolvedgases,wouldalwaysbegreaterthantheweightofthestartingmaterial.Lavoisier'sinterpretationwasmorereasonableandstraightforwardthanthatofthephlogistontheorists.Thephlogistontheory,alwaysclumsy,becamesuspect,eventuallyfellintoscientificdisrepute,andwasreplacedbynewideas.1.Whatdoesthepassagema
7、inlydiscuss?(A)Thechemicalcompositionofphlogiston.(B)Attemptstoexplainwhathappenswhenmaterialsburn.(C)Limitationsofseventeenth-centuryscientifictheories.(D)Thecharacteristicsoftheresidueleftafterfires.2.The
