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.

    Our school is a green school．What makes it green？

    First，we have a lot of trees．There are trees in front of and behind every building．Some trees are green only in spring and summer．And some are green all year round．The trees make our school look like a big forest.

    And our school is a green one because we "go green". How do we go green？We have two green days every month．On green days，no students or teachers go to school by car．And we have clean﹣up Day every month．That day，students go to streets to pick up rubbish．Also，we have tree﹣planting Day every spring．We plant young trees on hills．We have three green clubs The members of the clubs look after those trees well．

    Green is not only a colour．It is about life．Please go green with us and make the world a more beautiful place．

C

    In the future, your automobile will run on water instead of gas! You will be able to buy a supercomputer that fits in your pocket! You might even drive a flying car!

    For each prediction(预言) that has come true today, several others have missed by a mile. Many of these predictions didn't consider how people want to use the technology, or if people really needed it in their lives or not. Let's look at some predictions from the not-too-distant past.

    Robot helpers

    Where's the robot in my kitchen? Nowhere, of course. And he's probably not coming any time soon. Robots do exist today, but mostly in factories and other manufacturing environments.

    Back in the 1950s, however, people said that by now personal robots would be in most people's homes.

    So why it hasn't happened? Probably because robots are still too expensive and clumsy. And maybe the idea of robots cooking our dinners and washing our clothes is just too weird. At home we seem to be doing fine without them.

    Telephones of tomorrow

    In 1964, an American company introduced the video telephone. They said by the year 2000 most people would have a video phone in their homes. But of course the idea hasn't caught on yet.

    Why? The technology worked fine, but it overlooked something obvious: People desire for privacy. Would you want to have a video phone conversation with someone after you just stepped out of the shower?

    Probably not—it could be embarrassing! Just because a technology available(可利用的) doesn't always mean people will want to use it.

    Flying cars

    And finally, how about that crazy prediction of the flying car? It's not so crazy any more! But a flying car remains one of the most fascinating technology ideas to capture our imagination. Keep watching the news or perhaps the sky outside your window to see what the future will bring.