Today there are 6 billion people on the earth. By the year 2050 there may be 12.5 billion. There are a lot of people to feed. We need more food.

One way to produce more food is by growing stronger plants. For thousands of years，farmers have made plants better. Every season, they pick the best plants for the next season. It works very slowly. Since 1983, scientists have been able to change plants more quickly by changing their genetic material (遗传物质). Foods from plants grown in this way are called genetically modified foods (转基因食品), or GM foods.

    By changing the genetic material of a plant, it is possible to make new plants. They make plants which are strong against plant diseases. They can also help with our diseases: a kind of rice is being prepared, for example, which stops people from becoming blind.

    Rich countries produce GM foods because they are easy to grow and bring in more money. Poor countries are interested in them because they help produce more food.

    GM plants are not natural. No one knows how good or bad they are. Making GM foods is only one way of feeding people in 2050. There are strong feelings against them, because they are unnatural. They may feed people, and then hurt them or their children later. But, both rich and poor countries are very interested in their use, and they are not going to go away. In 2050, we may think differently about them.

    We have always been interested in the moon. 2000 years ago people already knew it moved around the earth and where it would be in the sky at different times of the year. At that time, everything about the moon was learned by watching it carefully in the sky.

    When scientists could use telescopes to study the moon more closely, their ideas began to change. They could see the moon was made of rocks. Most scientists thought moon rocks would be different from those on Earth. This was because they believed the moon had once been a planet that had been caught in the earth's gravity (引力) millions of years earlier.

    In 1969 moon rocks were finally brought to the earth and studied. Much to their surprise, scientists found that, except for water, the moon and the earth were made of the same things. Once again new ideas were needed for this new information.

    After years of study, most scientists now think that the moon was once part of Earth. They believe very early in its history, maybe 4 million years ago, something about the size of Mars hit Earth. This sent billions of rocks into space around our planet. These rocks slowly joined together and after many years became the moon.

    However, in the future, even though our ideas about the moon may change again, we will still be interested in it.

    In most parts of the world, many students help their schools make less pollution. They join "environment clubs". In an environment club, people work together to make our environment clean.

    ●No-garbage lunches. How much do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classes that make the least garbage and report them to the whole school!

    ●No-car day. On the no-car day, nobody comes to school by car—not the students or not the teachers! Cars give pollution to the air, so remember:

    Walk, jump, bike or run.

    Use your legs! It's lots of fun!

    ●Turn off the water! Did you know that some toilets can waste twenty to forty liters (升) of water an hour? In a year that would fill a small river! In environment clubs, students mend those broken toilets.

    We love our environment. Let's work together to make it clean.

    People don't like trash. Trash is smelly, dirty, ugly, broken and useless. That's why we throw it out. But everyone knows that trash influences our environment. It can pollute our land, water and air. So it's important to recycle our trash as much as possible.

    Some Americans were very interested in recycling and they were curious about what really happened to their trash. So, what did they do? They became detectives and decided to "Follow that trash!"

    They took some items out of their recycling bin and put electronic tags (标签) on them. The tags sent signals to a computer so people could follow their trash on its journey. They found that some trash only travelled a few kilometers but much of it went into landfills.

    Waste management companies in America think this detective work will be helpful to them. Dealing with waste is very expensive and this u trash tracking" will help them to become more useful. It will save their time and money.

    However, the trash detectives say it's also important to reduce the amount of trash we produce. After all, if we produce less waste, we won't have to worry about where it goes.

    Get a lot of letters at this time of year from people complaining (抱怨) that they have a cold and that it won't go away. There are so many ways to cure (治愈) a child. It is often difficult to know what to do. Although (尽管) cold are rarely (很少) dangerous, weak people , such as the elderly or young babies, often catch them. Colds are always uncomfortable and sometimes very unpleasant. Of course, you can buy lots of medicine. This will help to make your cold less unpleasant, but you must remember that nothing can actually cure a cold or make it go away quickly.

    Another thing is that any medicine can be dangerous if you are already taking another type of medicine for some other illness. So always check with your chemist (药剂师) or doctor to see if they are all right for you. Also, remember that they might make you sleepy; please don't try to drive it they do! Lastly, if you want to keep away from colds, don't blindly (盲目地) believe in 'magic' foods or drinks. The best way is to keep strong and healthy –you'll have less chance of catching a cold, and if you do, it shouldn't be so bad!