Animals are our friends. We can find different animals here and there. Some animals live in big forests(森林) and some animals live with man.

    Animals can help us a lot. Elephants can do some heavy work for us. And dogs can look after the home. The kids like dogs very much. Cats are women's favorite animals.

    We can eat their meat. We can make coats and shoes with their skins(皮). We can get milk from them. So man can't live without animals.

    In 1901, H. G. Wells, an English writer, wrote a book describing a trip to the moon. When the explorers (探险者) landed on the moon, they discovered that the moon was full of underground cities. They expressed their surprise to the "moon people" they met. In mm, the "moon people" expressed their surprise. "Why are you travelling to outer space when you don't even use your inner space?" they asked.

    H. G. Wells could only imagine the travel to the moon. In 1969, human beings really did land on the moon. People today know that there are no underground cities on the moon. However, the question that the "moon people" asked is still an interesting one. A growing number of scientists are seriously thinking about it.

    Underground systems (体系) are already in place. Many cities have underground car parks. In some cities, such as Tokyo, Seoul and Montreal, there are large underground shopping areas. The "Chunnel", a tunnel connecting England and France, is now completed.

    But what about underground cities? Japan's Taisei Corporation is designing a network of underground systems, called "Alice Cities". The designers imagine using surface space for public parks and using underground space for flats, offices, shopping and so on. A solar dome (太阳能穹顶) would cover the whole city.Supporters of underground development say that building down rather than building up is a good way to use the earth's space. The surface, they say, can be used for farms, parks, gardens, and wilderness. H. G. Wells's "moon people" would agree. Would you?

    Wind power is a very clean source of energy. This is how wind power works. Wind makes windmills spin (旋转). When the windmills spin, they make electricity. Then we can use the electricity.

    A lot of people think that wind power is new, but that's not true.

    For thousands of years, people have used wind to sail boats and move water. We still do those things today, but these days we mostly use wind power to make electricity.windmills

    Wind power is a very popular source of energy. Most people think that we should use it more and more. First of all, it's clean. Windmills don't pollute the environment at all. Second, we can use wind power forever. After all, we will always have wind. Also, wind power is cheap, and it's getting even cheaper.

    A lot of people don't understand wind power very well. They believe that there are problems with wind power, but many of those problems are not real. For example, some people say that windmills are dangerous for birds. They used to be true, but it isn't true anymore. Old windmills killed birds because they spun very fast. New windmills spin slowly, and they aren't dangerous for birds.

    However, there are real problems with windmills. One problem is that many people think windmills are very ugly. This is a problem for people, because windmills are often in very pretty areas. Also, wind doesn't blow all the time, so we can't use wind power all the time. Finally, windmills are noisy.

    Wind power is becoming more and more common. Right now, more than 80 countries use wind power. About 2.5 percent of the world's power comes from the wind. For some countries, that number is a lot higher. Wind power gives Denmark more than 25 percent of its electricity.

    Tigers are the largest wild cats in the world. They usually go out to hunt for food when it is dark. And they hunt alone most of time. When a tiger sees an animal, it moves quickly and then jumps on the animal to kill it. Sometimes it can take the tiger several days to finish eating its food. When the tiger is full, it will cover the dead animal with leaves. Later, when the tiger is hungry again, it comes back to eat some more.

    Tigers are different from others in the cat family. They like water and often jump into rivers to swim. Some tigers live in very cold places-in North Korea, Russia and China. Other tigers live in warmer places-in India and parts of Southeast Asia.

    But now all tigers are in danger. Some people kill tigers to use their skins for clothes, and their bodies for medicine. There is also less land for tigers to live on.

    Last year, a special kind of glove came out. It was invented to help blind people to learn Braille, which is a special system for the blind to read by touching. Shaking motors (震动马达) are put on each finger of the glove. They can make different sounds to tell a user which letter he is touching. Recently, two British college students have invented another special glove for the blind. It can make the user feel small and quick movements. An ultrasonic sensor (超声波传感器) with a battery is put on the back of the glove. When the user wearing the glove is close to an object(物体), ultrasonic waves (超声波) from the glove are sent out (发出). As soon as they hit the object in front, the waves will return to the glove. Then the waves cause the glove to shake. And the ultrasonic sensor makes different kinds of sounds. The sounds make the user know how far he is from the object.

    In the college invention competition, the two students got first prize and won 1,540 pounds. One of the designers said, "Now the ultrasonic sensor on the glove is quite large. We're going to use the money to develop a smaller and lighter ultrasonic sensor."

    Football is so popular in China. Almost everyone is interested in this sport—the young and the old, boys and girls, and now even robots.

Recently at Hangzhou Guangming Middle School, kids from several schools played football with their robots.

    Robot football is very different from human football. Only two robots play in each match. The field is as big as a ping pong table. One half is black and the other is white. Each robot tries to catch the "football" and score a goal. The robot with more goals wins.

    Gao Linge, a boy from Hangzhou Guangming Middle School, helped make one of the robots for the match.

    "My school bought the main board (主板),"said Gao, 14. "Then I decided what my robot looked like and made a computer program for it."

    Gao's robot was eight centimeters tall and had two arms. It had four sensors (传感器) to "see" and "kick" the "football".

    Ying Xuehai, a 12-year-old student from Gao's school, also made a robot. His robot played against Gao's. The match decided who would go to the final game. Ying lost the game. So he gave many of his robot's parts to Gao.

    Even so, Gao's robot didn't win the final. It played well in the first five minutes. Then it slowed down. By the end of the match, it could hardly move. What was wrong? Gao and Ying found the problem—the robot ran out of batteries (电池)!

    "We'll solve the problem and beat the other schools next time!" said the two boys.