题目内容：
根据以下材料，回答题 ExerciseCutsCancerDeathsinMen
Menwhoexerciseoftenarelesslikelytodiefromcancerthanthosewho（51）,newresearchpublishedintheBritishJournalofCancerrevealedyesterday.
AteamofscientistsfromtheKarolinskaInstituteinSwedenlooked（52）theeffectofphysicalactivityandcancerriskin40,708menaged（53）45and79.
Theseven-yearstudyfoundthatmen（54）walkedorcycledforatleast30minutesadayhada34percentlower（55）ofdyingfromcancerthanthemen．whodidlessexerciseornothingatall．（56）theperiodstudied,3,714mendevelopedcancerand1,153diedfromthedisease．Theresearcherssuggestthathalfanhour'swalking（57）cyclingadayincreasedsurvivalamongthesemenby33percent.
TheresearcherssurveyedmenfromtwocountiesincentralSwedenabouttheirlifestyleandtheamountof（58）activitytheywereusuallydoing．Theythenscoredtheseresponsesandcomparedtheresultswithdataoncancerdiagnosisanddeathofficiallyrecordedinacentralcancerregistry(登记薄)overaseven-year（59）．Leadauthor,ProfessorAlicjaWolk,said,"Theseresultsclearlyshowforthefirsttimetheeffectthatverysimpleandbasicdaily（60）suchaswalkingorcyclinghasinreducingcancerdeathriskinmiddle-agedandelderly（61）."
DrLesleyWalker,directorofcancerinformationatCancerResearchUK,said,"Thisstudygivesusaclearindicationthatmenwhoexerciseareless（62）todiefromcancer,andthattheyaremorelikelyto（63）thediseaseiftheygetit．It'snotentirelyclearfromthisstudywhatroleexerciseplaysinpreventing（64）inmen,butwedoknowthatahealthylifestylecanpreventuptohalfofallcancers--and（65）exerciseformsakeypartofthis."
回答(51)题 A．didn't
B．don't
C．won't
D．can't
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