4、Americans have never before exercised and dieted as eagerly as they are doing today．As a result, they do not only look younger and slimmer, but feel better．Because of increased physical fitness, life expectance in the nation has risen to seventy-three years, with fewer people suffering from heart disease, the nation's number one killer．

Jogging （ 慢跑 ）, the easiest and cheapest way of improving the body, keeps over 30million people of all ages on the run．For the price of a good pair of running shoes, anyone anywhere can join the race．

Dieting, too, has become a national  pastime．Promoters of diets that eliminate eating one thing or another, such as fats or carbohydrates （ 碳水化合物 ）, promise as much as 20- pound weight losses within two weeks．Books describing such amazing diets always head up （ 居……之首 ）the best-seller lists because people who are overweight want to lose weight quickly and easily．

Nevertheless, jogging and dieting, carried to extremes, can be harmful．Many confused joggers overdo and finally suffer from ankle and foot damage．Dieting, fortunately, becomes only a temporary means for shedding a few  pounds while the body lose the balanced nutrition （ 营养 ）it requires, so most dieters cannot keep on diets．Above all, common sense should be the keystone for any dieting and exercise plan．

1．The main idea of this passage is that___________ ．

       A．both jogging and dieting can improve your health

       B．exercise and improved diet has raised the American's life expectance

       C．people, who jog and diet wisely, will be healthier than those who do not

       D．diet and exercise harm rather than benefit health

2．According to the passage, which of the following statements is TRUE?

       A．Jogging can damage the body because it is too tough an exercise．

       B．Diets are so popular because they are on the best-seller lists．

       C．Americans now live to be 73 years old．                              

       D．Exercise and diet are more widespread in America than ever before．

3．It is implied but not stated that ___________ ．

       A．heart disease is the number one killer among Americans

       B．exercise and dieting bring about spiritual as well as physical well-being

       C．people don't stay on a diet because it doesn't work

       D．a 20-pound weight loss within two weeks is too much for the body

4．The best title for this passage is ___________ ．

       A．Jogging and Diet                                  B．Exercise and Health

C．Physical Fitness                                   D．Life Expectancy and Diet