Fifty years ago, most peoples daily levels of activity were equivalent to walking three to

Fifty years ago, most peoples daily levels of activity were equivalent to walking three to five miles a day. Today, the【C1】______person fails to 【C2】______ that distance in a week. Its 【C3】______the ratio of fatness has soared—with serious implications for health. What we have【C4】______ in convenience from labour-saving devices over the past half-century, we have paid for【C5】______ a sharp decline in physical activity. We use cars, buses or trains to【C6】______ work; our children are 【C7】______ to school; elevators and lifts have replaced【C8】______stairs in shopping centres, offices and apartment blocks. Washing machines, vacuum cleaners, dishwashers and electric mowers all reduce the effort required to【C9】______a clean and tidy home. Almost one third of adults 【C10】______ over ten hours sitting down every day,adding【C11】______a staggering average of 32 years and four months over a lifetime. 【C12】______ surprising, then, that researchers 【C13】______this lifestyle. for our weight gain. Of course, our diets have changed, too, 【C14】______the fact is that we consume fewer calories now than in the 1960s. So what is the 【C15】______？ The secret is integrated exercise. This【C16】______going about your normal daily life—but doing it with enthusiasm. It might mean standing to【C17】______the phone and tapping your feet on the floor as you work. It means never taking the car when you could walk; it means standing on short train and bus【C18】______, or walking at a pace【C19】______you feel you might break into a run if you were to go any【C20】______.

【C1】

A．average

B．common

C．familiar

D．normal

请帮忙给出正确答案和分析，谢谢！