题目内容：
根据以下材料，回答题Between1852,when(31)________wasfirstestablishedthatMountEverestwasthehighestmountainonearth,and1953,whenEdmundHillary,andTenzingNorgayfinallyreachedthepeak'ssummit,
itwaseverymountaineer'sdreamtobecomethefirstpersonstandingontheworld's(32)______point.AndGeorgeMallorywasoneofthemosttenaciousearlycontenders.
Mallorywasintroduced(33)_________rockclimbingwhilestudyingatWinchesterCollege.(34)________completedhisstudies,hesettledintoacareer(35)________ateacheratCharterhouseSchool,andcontinuedtopursuehispassion(36)_________climbinginhissparetime.
Mallory's(37)_________triptoEverestwasareconnaissancemissionin1921(38)_______aimedtoproducethefirstaccuratemapsoftheregion.Two(39__________visitstothemountainfollowed.Then,
on8June1924.(40)________histhirdattempttoreachthesummit,Malloryandhispartner,AndrewIrvine,disappeared.
Severalexpeditionssubsequentlyattemptedtofindthepair,andMallory's(41)________wasfinallydiscoveredinMay,1999,at8,169metres,600metres(42)________thesummit,(43)_________with
variousitemsofequipment,includinghandwrittenletterstohiswife,apocketknife,anoxygenbottleandhisgoggles,(44)________werelaterdonatedtotheRoyalGeographicalSociety
(45)________Mallory'sfamily.
Thereisstillconsiderabledebateasto(46)________MalloryreachedEverest'ssummit.The(47)___________thathisgoggleswerefoundinhispockethasledsometosuggestthathewasonhiswaydown
themountain(48)________hefell.Hadhebeenascendingindaylight,hewouldhavebeenwearingthegogglesto(49)_______snow-blindness,andgivenwhatisknownofthepair'sclimbingschedule,ifitwere(50)_______whentheyfell,theymusthavebeenontheirwaybackdown.
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