The population of the Earth is growing faster. It is important that we look after the Earth. We need it! The Earth gives us a lot of things. We also give the Earth a lot, but some of the things are not good.

   In nature, when something dies, other animals and plants get food from it. Every animal or plant gives food for other animals or plants. However, animals can't get food from many of the things that we "give" the Earth. Animals and plants can't eat metal, plastic and glass. These things will stay in the ground for many, many years.

   Some rubbish is very dangerous for plants and animals. In some places, many animals live together. One animal makes food for many more animals. If we put rubbish and chemicals in the water, the plankton(浮游生物) can die. If there isn't any plankton, many animals have nothing to eat.
   So what can we do? Don't leave any rubbish in the countryside! Don't make so much rubbish!

      Do you know how many pandas there are in the world? World Wildlife Fund (WWF) has spent four yours counting pandas in the world. It says there are 1,590 now. In the 1980s, there were only 1,100.

So we may say that pandas are lucky because people around the world love them and are trying their best to help them. However, we also say that pandas are unlucky because they are still facing a lot of problems now.

Pandas are not good at making babies. Even in the wild, scientists have found that female pandas give birth only every 28 months. That's why the number of pandas goes up so slowly.

Pandas need bamboos for food, but bamboo dies every 10 to 100 years. It can take up to 20 years to provide(提供) food for pandas. When bamboo dies, pandas have to move to other areas. In the past, this was easy. However, the number of people keeps growing, people cut down more forests and built more villages. It's more difficult for pandas to find bamboos and homes than before.

In the past years, WWF made great efforts to protect pandas. And some Chinese scientists are also always trying to find ways to help pandas.

    The Smallest Life Around Us

    Tiny plants and animals live all around us．We cannot see them because they are so small，but they are everywhere. They live in the soil，in the air，and in rivers and oceans．They grow on mountains and in caves．Some live in the ice at the north and south poles; some live where it is very hot．They are found throughout cities and in the country. They grow on other plants and animals．Some are even living on you，on your skin，hair，and inside your body，in your mouth，nose，and all through your body．

    These tiny plants and animals are called microbes．The word microbe is made from two other words：micro，meaning small，and bios，meaning life．So，microbe means small life．

    Microbes have been on earth for a very long time．They may have been the first forms of life to be alive．Today there are more microbes in the world than all other living things．

    People did not know microbes had existed（存在） long．They were too small for them to see．But people did see many changes in their world﹣important changes．And they did not know what caused them．They saw food that they kept too long change color and begin to smell bad．They saw cuts and wounds grow red and painful and become worse. They saw old plants and leaves and trees crumble apart on the forest floor and disappear into the soil．Such changes were a natural part of the world，but people did not understand them．They did not know these changes were evidence(证据) of tiny plants and animals growing all around them.

    You probably know many of the things that you can do with the hundreds of different muscles in your body. But have you ever thought about how the muscles in an animal's body are different from yours? An animal's muscles are made to do the things that are most important for its life.

    Lions are hunters. They depend on their ability to catch other animals. Lions must be fast in order to catch their prey(猎物). The powerful muscles in their back legs allow them to run at speeds of more than 30 miles per hour. They can also jump a distance of more than 35 feet. The strong muscles in their front legs help them catch their prey.

    Snakes also use their muscles for hunting prey and for movement, but their muscles work in very different ways than lions' do. Because snakes do not have any legs, they use their muscles to push against the ground or other objects to move themselves forward. Their muscles also allow them to eat things that seem much too large. For example, a snake may eat an egg that is larger than the width of its body. How does this happen? The snake's strong neck muscles work together to push the egg down the mouth.

    The elephant's long nose has a lot of muscles. Scientists believe that the nose alone has more than 100,000 muscles! This is because the elephant uses its nose much in the same way that people use their hands and fingers. Even though the nose is large, it can perform surprisingly tasks. For example, an elephant can pick up a small leaf from the ground. The nose can also be a powerful tool. An elephant can use its nose to pick up a tree by its roots or even to lift a baby elephant.

    The great muscles of these animals seem pretty unbelievable. But the muscles in your body work exactly the way you need them to. After all, it might be fun to be able to jump a distance of 30 feet, but as a human being, there is just not much need for it.

    Possible Earth-Like Planet Next Door?

    Scientists say they discovered an earth-like planet outside our solar system (太阳系). It is a planet that could support life.

    This planet is just 4.2 light years away from us. It is so close that space scientists have considered it as a next door neighbor. They say it could be reached by an unmanned spaceship before the end of the century -- in time for people alive today to see it.

    An international team of scientists found the planet moving around the star called "Proxima Centauri". The result came out last month from the scientific magazine Nature.

    Scientists have long thought that a planet with water is important for life. And it has to be neither too hot nor too cold. The newly-discovered planet is a little larger than earth Scientists have named it Proxima B. It moves around its sun, Proxima Centauri, once every 11 days.

    American scientists have been using instruments for years to look for earth-like planets. In 2013, scientists' best guess was that there are about one billion (1,000 million) "earths" in space.

    Alan Boss is the chairman of a group for outer space research. He said that Proxima B not only confirms (确认) the discovery of a planet, but also increases the number of other possible“earths” greatly.

    Boss said it is possible, even likely, that most stars have at least one earth-like planet, which he considers surprising.

    So from the early number of a billion, this new research suggests there may be as many possible earth-like planets as there are stars in the Galaxy (银河系). That is, anywhere from 250 billion to 500 billion "earths".

    This makes the possibility of living things increasingly likely Boss said he believes human beings will be able to show that there is life in places besides earth in his lifetime. "I am 65," he said, "but I expect to still be alive when it happens."