Common sense would tell us that physically active children may be more likely to become ac

tive and healthy adults.In the United States, elementary and middle schools are advised to give students two and a half hours of physical activity a week.That is what the Centers for Disease Control and Prevention and the American Heart Association recommend (推荐). They say high schools should provide about four hours of physical activity each week. Yet many schools across the country have reduced their physical education programs. Criticism of the cuts has led in some places to efforts to give students more time for exercise, not less.

The future health of Americans may depend on it. Just this week, a study reported that life expectancy (预期寿命) has fallen or is no longer increasing in some parts of the United States. The situation is worst among poor people in the southern states, and especially women. Public health researchers say it is largely the result of increases in obesity (肥胖), smoking and high blood pressure. They also blame differences in health services around the country.

In 2006, a study found that only four percent of elementary schools provided daily physical education all year for all grades. This was true of eight percent of middle schools and two percent of high schools. The study also found that 22 percent of all schools did not require students to take any P. E. (体育课).

Charlene Burgeson is the executive director of the National Association for Sport and Physical Education. She says one problem for P. E. teachers is that schools are under pressure to put more time into academic subjects. Also, parents may agree that children need exercise in school. Yet many parents today still have bad memories of being chosen last for teams because teachers favored the good athletes in class.

But experts say P. E. classes have changed. They say the goal has moved away from competition and toward personal performance, as a way tp build a lifetime of activity. These days, teachers often lead activities like weight training and yoga. Some parents like the idea of avoiding competitive sports in P.E class. Yet others surely dislike that idea. In the end, schools may find themselves in a no-win situation.

Why are schools recommended to give students certain time for sports？

A．Because different schools set up different physical education programs.

B．Because the physical activity of children will influence their health in adulthood.

C．Because nowadays children spend too much time on their studies.

D．Because only four percent of elementary schools provided daily physical education.