Why do plants grow in some places and not in the others? Why does some land have so much growing on it, while other land has almost no plants growing on it at all?

    To grow, plants need several things. One is warmth. In very cold places almost nothing grows. Plants also need water. In very dry parts of the Earth only a few unusual plants can grow. That's why dry deserts everywhere are almost not covered by trees or grass.

    Plants must also have a place in which to put down their roots and grow. They find it difficult to grow on hard land. The town is built on hard land. The plants here have only the soil found between the cracks of the stones to grow in.

    Another thing plants must have before they can grow is food.

What will happen if we try to make things grow on the sandy beach? A few plants, such as beach grass, will grow in sand, but most plants won't. Even if the weather is warm enough and we water the plants each day, many of them will die because the sand on this beach has almost no food for plants.

    Many people are surprised when they find that the Internet was set up in the 1960s. At that time, computers were large and expensive. Computer networks didn't work well. If one computer in the network broke down, then the whole network stopped. So a few network system had to be set up. It should be good enough to be used by many different computers. If part of the network was not working, information could be sent through another part. In this way computer network system would keep on working all the time.

    At first the Internet was only used by the government, but in the early 1970s, universities, hospitals and banks were allowed to use it, too. However, computers were still very expensive and the Internet was difficult to use. By the start of 1990s, computers became cheaper and easier to use. Scientists had also developed software that made "surfing" the Internet easier.

    Today it is easy to get online and it is said that millions of people use the Internet every day. Sending e-mails is more and more popular among young people. The Internet has now become one of the most important parts of people's life.

    In some science fiction movies, evil robots refuse to die, no matter how hard people fight back.

    Now science fiction has become science fact. For the first time, scientists have made a robot that can take a beating (挨打) and keep on going. Scientists from Cornell University made the robot, which looks like a spider with four legs.

    Until now, even the most advanced (先进的) robot was almost certain to break down when it was damaged. That is because its computer inside simply doesn't know how to make the machine work after its shape has changed.

    To deal with this problem, the scientists put eight motors (发动机) and two sensors (传感器) that read how the machine is working. They all give signals to the machine's software. Using this information, the computer can then figure out the machine's shape at any moment.

    The new technology is a big advance in robot-making, scientists say, and it's far from scary. It may someday help scientists create better artificial (假的) arms and legs and give new freedom to people who lose them. It might also help scientists understand how people and animals figure out their own sense of place in space.

    “It has been difficult to design robots that can work well when the environment changes or when it's damaged,” says Olaf Sporns of Indiana University in US. “With this work, we are nearer to solving this problem.”

    The Wandering Earth(流浪地球), China's first successful movie whose background is space, as shown on February 5. It is based on(基于)a short story of the same name by Liu Cixin, China's top  science—fiction writer.

    ⒈Capsule(太空舱)—a core(核心)element(要素)

    The space capsule used in the film has made the audience(观众)interested. "This was the first time anything like that was done, "said Wang Hong, the producer(制片人)of the movie. At first, the production(制作)team planned to use a small space capsule that had appeared in an earlier film, but found that it could not meet their needs for filming.

    ⒉Giant vehicles(巨大的车辆)—key to the film

    Giant vehicles are the key element in the film. Famous actors, Ng Man—tat and Wu Jing, said they could not even imagine what these vehicles would be like before filming, because the idea was far ahead of our time.

    The production team made about 10, 000 props(道具)to show the space better, including the giant vehicles.

    ⒊Saving planet itself

    In the film, the earth itself is pushed forward by 10, 000 giant

thrusters(推进器). It carries 3.5 billion people about 4.2 light years

through space in order to avoid destruction(破坏)by the dying sun.

In Liu's story, each thruster is 11, 000 meters in height.

    ⒋Amazing opening

    At the beginning of the film, it shows the environment and life in an

underground city—a big tree growing upside down, busy bookstores and snack bars and so on. There are also many snow scenes (片段)throughout the whole film.