Jogging has become the most popular individual sport in America. Many theories, even some mystical ones, have been advanced to explain the popularity of jogging. The plain truth is that jogging is a cheap, quick and efficient way to maintain physical fitness.

The most useful sort of exercise is exercise that develops the heart,lungs, and circulatory (血液循環的)systems. If these systems are fit, the body is ready for almost any sport and for almost any sudden demand made by work or emergencies. One can train more specifically, as by developing strength forweight lifting or the ability to run straight ahead for short distances with great power as in football, but running trains your heart and lungs to deliver oxygen more efficiently to all parts of your body. It is worth doing that: this sort of exercise is the only kind that can reduce heart disease, the number one cause of death in America.

Only one sort of equipment is needed - a pair of good shoes. Physicians advise beginning joggers not to try to run in tennis or gym shoes. Many design advances have been made in only the last several years that make a pair of excellent running shoes indispensable (不可缺少的) if a runner wishes to develop as quickly as possible,with as little chance of injury as possible. A pair of good running shoes will have soft pads for absorbing shock, as well as slightly built-up heels and full heel cups that will give the knee andankle more stability. A wise investment in good shoes will prevent blisters (水泡)and the foot,ankle and knee injuries and will also enable the wearer to run on paved or soft surfaces. No other special equipment is needed; you can jog in any clothing you desire, even your street clothes.

It takes surprisingly little time to develop the ability to run. The American Jogging Association has a twelve-week program designed to move from a fifteen-minute walk (which almost anyone can manage who is in reasonable health) to a thirty-minute run. A measure of common sense, a physical examination, and a planned schedule are all it takes.

1. The main purpose of this passage is to ________.

A. discuss jogging as a physical fitness program

B. describe the type of clothing needed for jogging

C. provide scientific evidence of the benefits of jogging

D. launch a worldwide physical fitness campaign

2. The most effective kind of exercise should be the one that ________.

A. trains the body for weight lifting

B. enables a person to run straight ahead

C. is both beneficial and inexpensive

D. develops the heart, lungs, and circulatory systems

3. What can we learn from the third paragraph?

A. For beginning joggers, tennis or gym shoes are better choices.

B. A pair of good running shoes is necessary for a runner to develop quickly.

C. A pair of good running shoes with a full heel-cup is designed to prevent shock.

D. Comfortable pads will give the knees and ankles more stability.

4. The author"s attitude towards jogging is ________.

A. doubtful

B. critical

C. approving

D. negative