Today, nearly five hundred weather stations in sixty countries receive satellite pictures.  When they receive new pictures, the meteorologists compare（比较）them with earlier ones.  Perhaps they may find that the clouds have changed during the last few hours.  This may mean that the weather on the ground may soon change, too.  In their next weather forecast, the meteorologists can say this.
　 So the weather satellites are a great help to the meteorologists.  Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours.  Now they can make good forecasts for three or five days.  Soon, perhaps, they may be able to forecast the weather for a week or more ahead（提前）.

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    Many years ago, there was a very popular sport in America. Who invented the sport more than 3,000 years ago? We don't know. But everyone thinks it was the Olmecs(奥梅克人）made it popular.

    People don't have the same rules about the game all over the world. People in different parts of the world play the game in different places at different times. If we want to bring back the sport, we need to have two teams of players standing on each end of a court. When the game begins, the two teams need to pass a ball from one side of the court to the other. The players can't touch(触) the ball with their hands and feet. But they can use their elbows(肘) and other parts of their bodies hit it. If a player does not pick up the ball in time and lets it fall to the ground, that team loses a point. But if a player makes the ball through a hoop(环),that team scores a point. The team with the most points wins the game.

    Watering plants is an important part of having a garden. But different plants have different needs. Plants like plenty of water, but how do you know what is too much or too little? Here are just a few helpful suggestions you may want to consider.

    3 Do's 3 Don'ts

    Water early.

    Water in the morning before it begins to get hot. It's a perfect time to water your plants. This way they are ready for the hottest parts of the day. Don't water too much.

    Although plants are usually thirsty, too much water can be harmful to their growth. If you notice the leaves are becoming yellow and falling off, it is a clear sign of too much water.

    Drain （排水） properly.

    Be sure to check the surrounding area of your plants regularly. The extra water should be drained well. Don't water late.

    This is especially important. Although not everyone will be able to do their watering in the early morning hours, try not to wait too late in the day. If you water in the afternoon when it is hot, lots of water will evaporate （蒸发）before reaching the roots. If you water in the evening, the roots will be too wet.

    Prevent insects.

    A thin, fine mist （喷雾） will prevent insects from setting on the leaves and flowers. Don't water the leaves.

    The most ideal place to begin is the root. This is where most of the growth and development takes place. In order for your plants to be strong, the roots have to be healthy.

    To really know what works well for your plants, watch them for signs of over watering or signs of not getting enough water. For more great advice on rose watering and growing roses, visit http:// www. my rose guide. com.

    We each have memory(记忆力).That's why we can still remember things after a long time. Some people have very good memories and they can easily learn many things by heart, but some people can only remember things when they say or do them again and again. Many of the great men of the world have got surprising memories.

    A good memory is a good help in learning a language. Everybody learns his mother language when he is a small child. He hears the sounds, remember them and then he learns to speak. Some children are living with their parents in foreign countries. They can learn two languages as easily as one because they hear, remember and speak two languages every day. In school it is not easy to learn a foreign language because the students have so little time for it, and they are busy with other subjects, too. But your memory will become better and better when you do more and more exercise.

    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."