完形填空
阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。
Walk a Quarter-Mile or Die
If you can walk a quarter-mile,odds（可能性）are you have at least six years of life left in you,scientists say.And the faster you can（51）it,the longer you might live.
While walking is no guarantee of（52）or longevity（长寿）,a new study found that the ability of elderly people to do the quarter-mile was an"important determinant（决定因素）"in whether or not they'd be（53）six years later and how much illness and disability they would endure.
"The（54）to complete this walk was a powerful predictor of health outcomes,"said study leader Anne Newman of the University of Pittsburgh School of Medicine."In fact,we（55）that the people who could not complete the walk were（56）an extremely high risk of later disability and death."
Newman and colleagues recruited nearly 2,700 white and African-American men and women aged 70 to 79 to（57）the walk.All the participants were screened and determined to be in relatively（58）health,and they had all said they had previously walked that far with no（59）.Only 86 percent of them finished,（60）.
The scientists then monitored the health and mortality of all（61）for the next six years."There was a big gap in health outcomes（62）people who could complete the longer walk and people who could not,with the latter being at an extremely high（63）of becoming disabled or dying,"Newman said."What was really surprising is that these people were not（64）of how weak they actually were."
Finishing times were found to be crucial,too.Those who completed the walk but were among the slowest 25 percent（65）three times greater risk of death than the speedier folks.
51.A.takeB.doC.jumpD.run
52.A.healthB.safetyC.peaceD.fun
53.A.oldB.effectiveC.alikeD.alive
54.A.taskB.standardC.abilityD.subject
55.A.foundB.doubtedC.suspectedD.studied
56.A.inB.atC.ofD.with
57.A.competeB.loseC.completeD.win
58.A.goodB.mentalC.physicalD.psychological
59.A.questionB.problemC.answerD.solution
60.A.henceB.moreoverC.howeverD.so
61.A.participantsB.activistsC.colleaguesD.athletes
62.A.forB.onC.amongD.between
63.A.numberB.gradeC.riskD.standard
64.A.sureB.freeC.stupidD.aware
65.A.increasedB.facedC.carriedD.avoided
