【答案解析】Nowadays, thousands of Americans indulge in the pursuit of slim bodies. They are possessed by on diet and exercise, which is not just the result of going in for young exterior. A recent research shows the extreme importance that on diet and exercise are of to keeping healthy. Like in many countries with highly developed industrial technology, the life style of North Americans has undergone dramatic changes. Modern machinery has completed physical work once done by compelled hands. We move fast from one place to another by cars and buses. Due to idleness, bodies become quite fragile and are inclined to sickness. To avoid the occurrence of such things, thousands of Americans devote more time in doing exercise. And the consequence brought by the realization of the importance of physical exercise is obvious: People who are walking and riding in parks are here and there; sport programs once again establish their prestige; many firms provide special sport equipments for their staff to do exercise during their working day.