Traffic problems are an everyday concern in many cities，including Washington，DC．A growing number of Washingtonians are turning to bicycles to get to and from work．In fact，the number of commuters who use bicycles has doubled in the city since 2007．

    Ralph Buehler teaches urban planning at the Virginia Polytechnic Institute and State University，popularly known as Virginia Tech．He has written a book about urban biking，calledCity Cyclin . g．He says there is a reason why urban bike tiding is now becoming more popular．

    “Over the last 60 to 70 years，cities in America have adapted to the automobile．”

    “Most cities took advantage of the money coming for the interstate highway system，from the federal government，  starting in 1956．There was a 90 percent federal match(补贴)so the cities only had to put up 10％．It was very tempting．”

    In the years after World War Two，many Americans moved to suburban communities，just outside major cities．They decided to travel great distances to and from work in exchange for a home in the suburbs．Their cars became a symbol of freedom．

    But today，many people believe they can save money by living in the city．

    Greg Billing is with the Washington Area Bicyclist Association．“When a person makes a change from using a car to using a bike，he／she is saving anywhere between 8 or $9，000 a year．”

    Ralph Buehler says governments save money when people use bicycles．“Building bicycling facilities is much cheaper than building and maintaining road facilities or public transport．”

    Washington，DC has also taken steps to protect bike riders．It approved a safe passing law and created areas on the road between cars and bikes．

    The United States Census Bureau says 4％of the city's workers ride to work by bike．The only city on the East Coast with more bike commuters is New York．

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    A report says older adults who test their minds with increasingly difficult projects have better mental ability than those who do less demanding activities.

    To keep our brains sharp as we age, we are often told to keep our minds active. As the old saying goes, “Use it or lose it.” But, there is very little scientific evidence to support than.

Denise Park is head of the university's Center for ? Vital Longevity. She designed a study in which she and her tern placed 221 healthy aging and older adults into one of three groups.

    “We asked people to learn new things, like quilting or photography. We asked other people to just do fun things like being in a social group function but were not likely to have a very large effect.”

    The subjects took part in their assigned activities for 15 hours a week over three months. At the end of that time, the researchers found that the adults who learned new skills, such as digital photography, showed the greatest improvements on memory tests.

    No improvements were seen in the results of those in the social group that did activities together like going on field trips. There were also no improvements among the third group that listened to classical music or did crossword puzzles.

    Denise Park believes one reason for improved memory in the active learning group is that its members were being pushed to learn new skills. The other groups took part in what she call receptive activities. Learning new skills may not cure age-related mental decline. But, Ms. Park thinks being mentally active slows down the process.

Denise Park says the latest information shows that the improvements lasted for at least a year. She and her team plan to do longer follow-up studies with all three groups. She also is interested in learning whether taking part in demanding mental activities delays the development of conditions like Alzheimer's disease.

    The Healthy Habits Survey shows that only about one third of American seniors have correct habits. Here are some findings and expert advice.

You might think people all over the United States have Wi-Fi—wireless Internet service—and mobile phones. But there is no such service in Green Bank, West Virginia, a tiny town four hours from the U.S. capital, Washington D.C. Fewer than 150 people live in Green Bank, which has two churches, an elementary school and a public library. It is also home to the largest radio telescope in the world.

    There is a ban on Wi-Fi in Green Bank, along with anything else that can create electromagnetic(电磁的)waves. Officials say the waves could disturb the signals the telescope receives.

For many Americans, a visit to Green Bank is a little like returning to the 1950s. To get there, you must read road signs—because there is no GPS service in the town. People can connect with the Internet through telephones, but wireless service is not allowed.

    The observatory(天文台)is one of the largest employers in the area. The federal National Science Foundation(NSF) spends about ＄8.2 million a year to operate the observatory, telescope and educational center.

    Jonah Bauserman is a technician. If he supposes there is signal that is not allowed in the zone, he drives to the house where the signal is coming from and checks it. But once a week, when the device is cleaned, some banned devices are allowed near it.

    People in the town respect the work of the scientists. And they say they are happy to live without Wi-Fi and mobile phones. “You know, instead of sitting here on our phones and other devices we're out fishing and hunting and going to each other's houses.” Everyone knows each other and communication is almost always face-to-face.

    Physical education, or PE, isn't required for all high school students. In some schools, it isn't offered for some different reasons. But should high school students have physical education? The answer is certainly "yes".

    Today many people don't do sports. But as is known to all, doing sports is very important for an adult. Teaching teens the importance of a healthy lifestyle and making fitness plans now can help teens put exercise in the first place as an adult.

    High school isn't that easy. Many students are under a lot of stress. Stress can be harmful to a student's studies and life. Doing sports can help them deal with stress better, helping them live a happier life at school.

    The American Heart Association says that 10 million kids and teens suffer from obesity (肥胖症). Teens should get 60 minutes of physical activity per day to control their weight and to help their bones get stronger. The increase in activities that don't get teens to move around, such as video games and computer activities, means many teens don't get their required exercise. PE classes act as a public health measure to encourage physical activities and help teens have healthy weights.

    Not doing sports increases teens' risk of developing many diseases. An active lifestyle offers a good way of protection from these health problems. As much as 75 percent of health-care spending goes toward treating medical conditions that can be hindered by lifestyle changes, according to the American College of Sports Medicine.

    According to the President's Council on Fitness, Sports and Nutrition (PCFSN), students who performed five hours of physical activity each week improved their academic (学业的) performance. Students from programs with no physical activity, who used the extra time for classroom study, did not perform better on tests than those who gave up some study time in support of physical education.

The success of The Pickwick Papers made Dickens very popular. He suddenly found himself at twenty-four the most famous novelist of his day. Busy as his social life was, he worked on two novels at the same time—Oliver Twist and The Pickwick Papers. He was particularly proud of The Pickwick Papers, which was a huge success and was regarded as a comedy (喜剧) masterpiece (杰作). "If I were to live a hundred years and write novels in each, I should never be so proud of any of them as I am proud of The Pickwick Papers," he said.

It has been said of Dickens that he grasped (抓住) the imagination of his readers because his imagination grasped himself. The people in his works were so real that they could make him laugh or cry. When writing Oliver Twist he said that he could not rest until Fagin, the wrongdoer (做坏事的人), had been hanged.

Dickens' marriage to Catherine Hagarth, with whom he had ten children, ended unhappily in 1858. He started to travel about giving readings of his works. His interest in theater gave his novels the qualities that made them suitable for reading aloud on the stage. A tiring travel to the United States affected his health. On June 9, 1870, when he was working on a new novel, he died, as he had wished. He said he wanted to die working.