A、Walking is the world’s most natural exercise. B、Walking is not so dangerous as running. C、Walking will bring less physical har

Many people in the world walk to work or to school. They have no other form of transportation. Many others, however, travel by bus, train or car. They walk very little. Yet experts say walking is one of the best ways to stay healthy. They call it the world’s most natural exercise. Walking is less dangerous than running. It strengthens muscles without stretching them too much. And it puts less pressure on bones and joints. About fifty million Americans are active in what is called "fitness" walking. They take short walks a few times each week to improve their health. Fitness walking can be done almost anywhere, anytime. No special equipment is needed. Experts advise drinking lots of liquids, especially water, before and after each walk. Also, gently stretch the muscles and joints that are most likely to become tense during exercise.
Experts say the most effective way to walk is the natural way. Keep your head high and your back straight. In fitness walking, it is important to remember that your footsteps should fall almost in a straight line. Bend your arms at the elbow. Let them swing from the shoulder with each step. Walking is good for the health of your body. And a new study provides details about the link between walking and your emotional health. Robert Thayer of California State University asked a group of students to describe their feelings of energy and tension. Then he sent the students on a fast walk for ten minutes. When the students returned, they reported feeling less tired and more full of energy.
   Professor Thayer found that short walks can also help make personal problems seem less serious. One group of persons described the seriousness of their personal problems, such as job worries or a failing marriage. Then they went for a fast ten-minute walk. When they returned, they said their problems seemed less threatening. Improvements were not observed every day. But after three weeks, the differences became very clear.
23.Which of the following statements about walking is NOT true?
24.Which of the following statements about fitness walking is NOT true?
25.How did the students in the experiment feel after they took a fast walk for ten minutes?
26.What did Professor Thayer find in the experiment?