题目内容：
回答题：Active in Old Age Keeps People Mobile
People over 70 who aren't active are more likely to develop problems walking or climbing stairs within a few years, according to a new study.
These findings suggest that it's very important to stay_________ （51） in old age, study author Dr. Marjolein Visser told Reuters Health.
"Physical activity in old age is as important _________（52） taking your medications（药物）," Visser noted. "You do not need to join an expensive, fancy sports club with high-tech （高科技的） equipment. Your body will already_________（53） from regular walking."
Visser, a Dutch （荷兰的） scholar, explained that_________（54） active helps prevent people from becoming breathless during simple activities, increase muscle mass and strength, and maintain the balance people need to walk up stairs, for instance.
To investigate how important exercise is to older adults, Visser's team interviewed 3,075 men and _________（55） between the ages of 70 and 79, all of whom said they had no problems walking one-quarter of a mile or climbing_________（56）. The investigators followed the subjects for 4-1/2 years, noting who developed problems _________（57） and climbing stairs.
During the study, 34 percent of men and 47_________ （58） of women said they began to struggle with walking and climbing stairs. People _________（59） were inactive were twice as likely to report these problems as people who said they got regular exercise.
People who didn't exercise but had active lifestyles appeared to be at a somewhat higher risk of developing _________（60） walking and climbing stairs, relative to people who exercised_________（61）. Still, leading an active lifestyle appeared to protect people _________（62） problems better than being generally inactive, the researchers report in the Journal of the American Geriatrics （老年医学） Society
Among people who were inactive, _________ （63） who walked even a little bit such as brisk （轻快的） walking for a little over an hour per week - were at a lower_________ （64） of mobility （可动性） problems.
"If you do not like to exercise or you cannot exercise _________（65） of serious health problems or functional limitations, do try to be as active as possible, " Visser advised.
A．young
B．new
C．still
D．active
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