Where does the wind come from? What makes the wind move(移动) all the time? Scientists tell us that it is the sun. That makes air move, and makes it blow(吹). When the sun shines on the earth, it makes the earth hot. Then the earth makes the air hot. When the air becomes hotter, it also becomes lighter(更轻). The light air goes up. Cool air comes into take the place of（代替） the hot air. The hot light air goes up higher and higher until it becomes cool. Then it comes down again, and then the earth makes it hot again, and it has to go up. When the air move, it has wind.

    We have known for a long time that flowers of different plants open and close at different time of day. Yet no one really understands why flowers open and close like this at special times. It is not as simple as we might think, as new experiments(实验) have shown. In one experiment, flowers were kept in darkness. We might expect that the flowers, without any information about the time of the day, did not open as they usually do. In fact, they continued to open at their usual time. This shows that they have some mysterious (神秘的) way of knowing the time.

    Their sense of time does not depend on information from the outside world; it is, so to speak, inside them, a kind of “inner clock”. This discovery may not seem to be very important. However, it was later found that not just plants but also animals including man have this “inner clock”which controls(控制) working of their bodies and their activities.

    Human beings, then, are also controlled by this mysterious power. Whether we wish it or not, it affects such things in our life as our need for sleep, our need for food. And our ability to concentrate(集中).

An invention in front of your eyes

    What is the most important invention of all time? Is it the written word that helps us to record information? Is it the telephone that lets us talk to people from all over the world? Is it the car that lets us travel at great speeds to meet others? Umberto Eco, an Italian writer, thinks it is something quite different. He says the most important invention might be bright in front of your eyes. He is talking about a simple pair glasses.

    Modern eye glasses were invented around 1000years ago. They were more than just a convenient way to read. Before glasses, writers, scientists or teachers who could not see properly had to memorize everything. After about ten years of poor eyesight, they could not remember well enough and could not work. Glasses meant that people could work in their old age.

    People who wanted to remember some information could write it down and read it. Eye glasses are one of the world's greatest inventions and were probably worn by the people who designed the first telephones and cars.

    How green are you? Do you know how to be green?

    We all need a healthy environment, but we produce waste every day and it does harm to our environment. Though we are young，we can still do something to help. In fact, even the simplest everyday activities can make a real difference to the environment. Here are some ideas for you.

    Reduce

    Reduce means "use less". Don't waste things. This saves money and reduces pollution and waste going into the environment. Before we buy something new, think whether it is really necessary-or maybe the old one will be just as good! When we buy things, choose local products if possible, and try not to buy too many things from abroad.

    Reuse

    Reuse means "use again". Use things for as long as possible. When we buy things, make sure that they last a long time. We should look after them so that they will last, and we should repair them if we can instead of throwing them away and buying new ones. Don't use a paper cup or a paper bag. It's better to use a china(瓷器) cup and a lunch box because you can use them again.

    Recycle

    Recycle means "change things into something else". Though it takes energy to change something into something else, it's better than throwing things away or burning them. Find out what can be recycled in your neighborhood and take part in recycling programs. We should also buy products made from recycled materials, such as recycled paper, to help save trees.

    So please remember these three words: reduce, reuse and recycle.