The earth is about 4,600 million years old. Modern man has lived on the earth for only 35,000 years, but during that time, we have changed our planet in many ways. Many of the things that we have done are good, but more are not good for the earth.

    Water pollution

    A lot of people, birds and fish die each day because of water pollution. Factories have polluted the land and the water. As a result, many river and lakes are now dead.

    Air pollution

    In big cities, factories, as well as cars, trucks and buses are the biggest cause of air pollution. Many people in cities now have bad health problems. For example, Mexico city used to be a beautiful sunny capital, but today it is almost covered by thick brown clouds.

    Soil pollution

    In order to have a good harvest, most of the farmers use chemicals too much on their fields. That's bad for the soil. But this kind of pollution is difficult to stop.

    Hope for the future

    These problems are very serious for our future, so all of us should do something to improve our environment. If we can stop pollution, our planet will become more and more beautiful and our health will be better. Let's be greener people.

    Scientists in Britain and the United States have made a new kind of enzyme(酵素) that eats plastics(塑料). With its help, plastics can be turned into smaller parts and go away quickly.

    Scientists believe that, in the future, it could solve the problem of plastic pollution.

    The enzyme is able to break down PET, a form of plastic. PET was first made in the 1940s and is now widely used to make plastic bottles. It can remain in the environment for many years and pollute large areas of land and water. So it has always been a headache to deal with the waste from PET and other plastics.

    The researchers made the discovery(发 现) while examining the structure of a natural enzyme in Japan. They found that the natural enzyme was helping to break down PET plastics. So, they

decided to make small changes to the enzyme by adding some amino acids(氨基酸). It made the natural enzyme's plastic-eating abilities work faster and better.

    John McGeehan, one of the lead researchers, said, "We've made an improved enzyme. It's better than the naturl one. And we are trying to make more improvements to it." He went on."

    The enzyme is not harmful to humans or animals, and it is friendly to the environment. So we are considering putting it into wider use."

    The team is now trying to make the enzyme break down PET in large quantities(大量的). "We'll see that the plastic pollution may be stopped with this technology. However, there is still a long way to go," John McGeehan added.

What would you do if you see someone hurt badly? The following will help you to learn some important skills to give casualty (伤员) first aid.

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The first and most important thing you must do is to make sure the place is not dangerous. Can you see anything that might not be helpful to you? Can you hear anything that could be dangerous?

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When you see someone has been hurt, you may feel scared. If you feel yourself starting to be nervous, try to calm yourself down. For example, talk to people you trust about what happened, and you'll be relaxed.

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When someone needs first aid, talking to him will help him to stay calm and feel safe. Even if he does not answer you, you should still tell him what you are doing. It will let him know that you are helping him.

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Sometimes, the casualty will need more help than you are able to give. The best thing you can do is to phone some people for help. They can give you some useful advice or offer you some help.

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There are also many other things to do. Try your best to help the casualty. Asking people around you for help is really better than waiting for doctors. Besides, you can also try to keep in touch with his families and friends.

Until the beginning of July, there has been no rain in northern Italy for over 100 days. Add to that the high temperatures, and the locals get very dry conditions. This is the most serious dry spell（干旱期）for that area in the past 70 years. Because of this situation, the country's longest river, the Po, is drying up!

This is bad news for several different reasons. The fresh water of the Po provides drinking water for northern Italy. Besides, farmers in this area need the water of the Po to keep their crops growing. What's more, the flowing river water is used to create about half of the hydroelectric power（水力发电）for Italy. Its drying up means that more natural gas（天然气） will be used, which is bad for the environment.

There have been some interesting discoveries from this lack of rain, however. Between Florence and Milan, a long ship sunk （沉没）in 1943 appeared because of the low water levels of the river. Now many tourists and locals come to see this ship. A German tank has also appeared out of water near Mantua. At other places along the river, people can even walk on the sandy river bed. Although this may be interesting, people in Italy and around the world are hoping for the return of rain to refill the Po!