Space is where our future is — trips to the Moon, Mars and beyond. Most people would think that aside from comets(彗星) and stars, there is little else out there. But, since our space journey started we have left so much trash(垃圾) there that scientists are now concerned that if we don't clean it up, we may all be in mortal(致命的) danger.

    The first piece of space junk was created in 1964, when the American satellite Vanguard Ⅰ stopped operating and lost its connection with the ground center. However, since it kept orbiting around the Earth without any consequences, scientists became increasingly comfortable abandoning(抛弃) things that no longer served any useful purpose in space.

    It is estimated(估计) that there are now over 500,000 pieces of man-made trash orbiting the Earth at speeds of up to 17,500 miles per hour. The junk varies from tiny pieces of paint chipped off rockets to cameras, huge fuel tanks, and even odd items like the million-dollar tool kit that astronaut Heidemarie Stefanyshyn Piper lost during a spacewalk.

    The major problem with the space trash is that it may hit working satellites and damage traveling spacecraft(飞船). Moreover, pieces of junk may collide(碰撞) with each other and break into pieces which fall back to the Earth. To avoid this, scientists have invented several ways for clearing the sky. Ground stations have been built to monitor larger pieces of space trash to prevent them from crashing into working satellites or space shuttles. Future plans include a cooperative effort among many nations to stop littering in space and to clean up the trash already there.

    For most city people, the elevator is an unremarkable machine that inspires none of the enthusiasm or interest that Americans afford trains, jets，and even bicycles. Dr. Christopher Wilk is a member of a small group of elevator experts who consider this a misunderstanding. Without the elevator, they point out, there could be no downtown skyscrapers or tall buildings, and city life as we know it would be impossible. In that sense, they argue，the elevator's role in American history has been no less significant than that of cars. In fact, according to Wilk_? the car and the elevator have been locked in a “secret war” for over a century, with cars making it possible for people to spread horizontally (水平地)，and elevators pushing them toward life in close groups of towering vertical (垂直的)columns.

    If we tend to ignore the significance of elevators, it might be because riding in them tends to be such a brief, boring, and even awkward experience^one that can involve unexpectedly meeting people with whom we have nothing in common, and an unpleasant awareness of the fact that we're hanging from a cable in a long passage.

    In a new book, Lifted, German journalist and cultural studies professor Andreas Bernard directed all his attention to this experience, studying the origins of elevator and its relationship to humankind and finding that riding in an elevator has never been a totally comfortable experience. “After 150 years, we are still not used to it”， Bernard said. “We still have not exactly learned to cope with the mixture of closeness and displeasure.” That mixture, according to Bernard, sets the elevator ride apart from just about every other situation we find ourselves in as we go about our lives.

    Today，as the world's urban population explodes，and cities become more crowded, taller, and more crowded, America's total number of elevators—900,000 at last count, according to Elevator World magazine's “2012 Vertical Transportation Industry”一are a force that's becoming more important than ever. And for the people who really, really love them, it seems like high time that we looked seriously at just what kind of force they are.

    Miss Parker taught physics in a New York school. Last month she explained to one of her classes about sound ,and she decided to test them to see how successful she had been in her explanation. She said to them, “Now I have a brother in Los Angeles. If I was calling him on the phone and at the same time you were 75 feet away, listening to me from across the street, which of you would hear what I said earlier, my brother or you and for what reason?”

    Tom at once answered, “Your brother. Because electricity travels faster than sound waves.”“That's every good,” Miss Parker answered; but then one of the girls raised her hand, and Miss Parker said.“Yes, Kate.”

    “I disagree,” Kate said.“Your brother would hear you earlier because when it's 11 o'clock here it's only 8 o'clock in Los Angeles.”

    The fried foods, salty snacks and meat are major foods of the Western diet, which account for about 30 percent of heart attack risk across the world. Meanwhile, a diet rich in fruits and vegetables, the so called "Prudent" diet, can lower the risk of heart attack, according to a study.

    The research which looked at dietary habits in 52 countries, found people who ate a Western diet had a 35 percent greater risk of having a heart attack, compared to those who ate little or no fried foods and meat. Those who followed a "Prudent" diet had a 30 percent lower risk of heart attack, compared to those who eat little fruits and vegetables.

    The authors also looked at an "Oriental" diet, rich in tofu, soy and other sauces (酱类), and found it did not increase or decrease the risk of a heart attack.

    Previous studies have reached similar conclusions about the "Prudent" and Western diet in the United States and Europe, but did not include the Oriental pattern of eating. While some food of the Oriental diet may protect against heart trouble, the higher sodium (钠)content of sauces counter(抵消) that benefit.

    "This study indicates that the same relationships that are observed in Western countries exist in different regions of the world, "a professor of medicine at McMaster University said.

    Canadian researchers analyzed risk factors in food choices and the risk of heart attack in about 16, 000 people in 52 countries. Almost 6, 000 people had heart attacks, while the rest had no heart disease.

    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.

    "Don't answer it," I said to Sam. Our door in the inner city is constantly knocked on; our previous door in the suburbs rarely so. Sam has a full-time job and cannot spend his days answering requests to fix leaking baths or carry cash to the bank.

    Sam opened the door and it was Mervin.

    "There's a bird on the second floor," he said. "It's in trouble."

    Sam followed Mervin upstairs. Mervin pointed and turned to let Sam look. It was a pigeon, the most common of all birds, the bird most likely to foul (弄脏) your newly washed car. And it wasn't flying away. It was stamping in circles. As Sam bent to look, Mervin coughed, "Number two."

    Sam asked him to repeat that. "Number two," Mervin said. "The pigeon has been sitting in his own number two, and now it's stuck to his foot."

It had rained for five days, and the bird was young. It could have been sheltering in a     wet nest of its own waste, which had then dried on its foot, preventing it from flying away. The pigeon moved in a few more circles. Sam bent to take another look. Mervin said, "All right, then." and walked away.

    "Why does everyone think you must solve the problems around here?" I said to Sam when he returned with his story. "It's a bird. Just leave it on the stairs, and let nature take its course." Sam didn't agree. Then he went to the garage and emptied the cardboard box containing our imported camping mats. He returned with the gray pigeon in the box. He showed the bird to our children and they decided to keep it.

    They put its foot in the warm water bath and got rid of its waste. Immediately the pigeon erupted in a bomb of feathers and began flying.