Electrical devices (仪器) could soon use power made by human energy. Scientists say they have developed an experimental device that produces electricity from the physical movement of a person walking. British scientist Max Donelan and other scientists in Canada and the United States developed the device.

    The device connects to a person's knee. As the person walks, the device captures energy each time the person slows down. To do this, the device helps with the slowing down movement of the leg. The movements of the walking person push parts of a small machine that produces electricity. Using the device, an adult walking quickly could produce thirteen watts of electricity in just a minute. Donelan says walking at that speed could produce enough power to operate a laptop computer for six minutes.

    There are several possible uses for the device. Developers say it could help people who work in areas without electricity to operate small computers. The device could also be used in hospitals to operate heart pacemakers (起搏器). It could even be used to assist in the movement of robotic arms and legs.

    The experimental version of the device weighs about one and a half kilograms, but it is too costly for most people to buy. But the researchers hope to make a lighter, less costly version. An improved version should be ready in one year.

    The developers hope the device will one day help developing countries. Nearly twenty-five percent of people around the world live without electric power.

    A similar product was invented in 2005 by Larry Rome of the University of Pennsylvania. He created a bag carried on a person's back that also produces power from walking. The knee device does not produce as much electricity as the bag. But the bag requires the walker to carry a load of twenty to thirty kilograms.

    By the mid-nineteenth century, the term “icebox” had entered the American language, but ice was still only beginning to affect the diet of ordinary citizens in the United States. The ice trade grew with the growth of cities. Ice was used in hotels, pubs, and hospitals, and by some forward-looking city dealers in fresh meat, fresh fish, and butler. After the Civil War (1861-1865), as ice was used to refrigerate freight cars(货车), it also came into household use. Even before 1880, half the ice sold in New York, Philadelphia, and Baltimore, and one-third of that sold in Boston and Chicago, went to families for their own use. This had become possible because a new household convenience, the icebox, a precursor（前身）of the modem refrigerator, had been invented.

    Making an efficient icebox was not as easy as we might now suppose. In the early nineteenth century, the knowledge of the physics of heat, which was essential to a science of refrigeration, was undeveloped. The common belief that the best icebox was one that prevented the ice from melting was of course mistaken, for it was the melting of the ice that performed the cooling. Nevertheless, early efforts to economize ice included wrapping the ice in blankets, which kept the ice from doing its job. Not until near the end of the nineteenth century did inventors achieve the delicate balance of insulation(绝缘) and circulation needed for an efficient icebox.

    But as early as 1803, an intelligent Maryland farmer, Thomas Moore, had been on the right track. He owned a farm about twenty miles outside the city of Washington, for which the village of Georgetown was the market center. When he used an icebox of his own design to transport his butter to market, he found that customers would pass up the rapidly melting butter of his competitors to pay an extra price for his butter, still fresh and hard in neat, one-pound bricks. One advantage of his icebox, Moore explained, was that fanners would no longer have to travel to market at night in order to keep their produce cool.

    Drive through any suburb in the U.S. Today, and it's hard to miss the recycling bins that have become companions to America's trash cans. Recycling has become common, as people recognize the need to care for the environment. Yet most people's recycling consciousness extends only as far as paper, bottles, and cans. People seldom find themselves facing the growing problem of e-waste.

    E-waste rapidly increases as the techno- fashionable frequently upgrade to the most advanced devices, and the majority of them end up in landfills (垃圾填埋地). Some people who track such waste say that users throw away nearly 2 million tons of TVs, VCRs, computers, cell phones, and other electronics every year. Unless we can find a safe replacement, this e-waste may get into the ground and poison the water with dangerous toxins (毒素), such as lead, mercury, and arsenic. Burning the waste also dangerously contaminates the air.

     However, e-waste often contains reusable silver, gold, and other electrical materials. Recycling these materials reduces environmental problems by reducing both landfill waste and the need to look for such metals, which can destroy ecosystems.

    A growing number of states have adopted laws to ban dumping e-waste. Still, less than a quarter of this waste will reach lawful recycling programs. Some companies advertising safe disposal in fact merely ship the waste to some developing countries, where it still ends up in landfills. These organizations prevent progress by unsafely disposing of waste in an out- of- sight, out- of- mind location.

    However, the small but growing number of cities and corporations that do handle e- waste responsibly represents progress toward making the world a cleaner, better place for us all.

    Good health is the most valuable thing a person can have but one cannot take good health for granted. It is important to remember that the body needs proper care in order to be healthy. There are three things that a person can do to help stay in good shape, eat right food, get enough sleep, and exercise regularly.

    Proper nutrition is important for good health. Your body cannot work well unless it receives the proper kind "fuel". Don't eat too much food with lots of sugar and fat, eat plenty of foods high in protein, like meat, fish, eggs and nuts. Vegetables and fruits are very important because they provide necessary vitamins and minerals. However, don't overeat It is not helpful to be overweight

    Getting the proper amount of sleep is also important. If you don't get enough sleep, you feel tired and easily get angry. You have no energy. Over a long period of time a little amount of sleep may even result in a change of personality(人的个性).Be sure to allow yourself from seven to nine hours of sleep each. If you do, your body will feel strong and refreshed, and your mind will be sharp.

    Finally, get plenty of exercise. Exercise firms the body, strengthens the muscles, and prevents you from gaining weight. It also improves your heart and lungs. If you follow a regular exercise program, you will probably increase your life-span(寿命). Any kind of exercise is good. Most sports are excellent for keeping the body in good shapes: basketball, swimming, bicycling, running and so on. Sports are not only good for your body, but they are enjoyable and interesting, too.

    If everybody were to eat the right foods, get plenty of sleep and exercise regularly, the world would be a happier and healthier place. We would all live to be much older and wiser.

    It seems that no one can live a happy life without friendship. While a great number of people expect others to be their friends, they don't give friendship back. That is why some friendships don't last long. To have a friend, you must learn to be one. You must learn to treat your friend the way you want your friend to treat you. Learning to be a good friend means learning three rules: be honest; be generous; be understanding.

    Honesty is where a good friendship starts. Friends must be able to trust one another. If you do not tell the truth, people usually find out. If a friend finds out that you haven't been honest, you may lose your friend's trust. Good friends always depend on one another to speak and act honestly.

    Generosity means sharing and sharing makes a friendship grow. You do not have to give your lunch money or your clothes. Naturally you will want to share your ideas and feelings. These can be very valuable to a friend. They tell your friend what is important to you. By sharing them, you help your friend know better.

    Sooner or later everyone needs understanding and help with each other. Something may go wrong at school. Talking about the problem can make it easier to solve. Turning to a friend can be a first step in solving the problem. So to be a friend you must listen and understand. You must try to put yourself in your friend's place so that you can understand the problem better.

    No two friendships are exactly alike. But all true friendships have three things in common. If you plan to keep your friends, you must practice honesty, generosity and understanding.

Emily, a 14-year-old teenager, walked through her town one afternoon. Her eyes were drawn to the sight of people without homes on street corners, trembling（颤抖） against the chill. It was a scene that stirred something deep within her—a desire to make a difference, no matter how small.

Emily decided to turn her love of baking into a force for good. She whipped（搅打） cream, mixed flour, and baked cookies and cakes in her family kitchen. With the support of her friends and family, she set up a colorful stall in her bustling neighborhood, offering her homemade treats to passersby in exchange for donations.

The response was overwhelming. People were not only touched by Emily's handmade cookies but also inspired by her spirit. Before long, donations were pouring in. In just a few short weeks, Emily had raised over $1,000—a symbol of one's kindness to ignite a community's generosity.

But Emily's heart was set on doing even more. Inspired by the success of her bake sale, she came up with the idea of organizing a charity run. A community-wide event that would bring people together in support of a common cause. She reached out to local businesses and called for volunteers to help her realize the project. On the day of the charity run, participants ran under the clear, open sky, and the running campaign raised over $5,000 for the local homeless shelter.

For Emily, the true reward lay not in the dollars raised or the miles run but in the knowledge that she had touched the hearts of her community and shown that even the smallest act of kindness can make a difference to the world.