Your body is special – no two people in the world are alike, Although you are different from everyone else, you have exactly the same body parts as the people around you, doing different jobs that keep all of us alive.
    What is inside my head ?
    Your head houses the most valuable part of your body – your brain. As you are reading, your eyes send pictures to your brain which makes meaning from what you see. Your brain helps you to remember and think, and makes sure your body is doing what it should.
    What is my skin(皮肤) for ?
    Your skin covers your body. In most parts of your body, the skin is just as thick as half a centimeter. If you have your skin cut, it will have a quick cure and stop viruses from getting into your body. Your skin also helps you feel the heat and coldness of the environment around you. Hair grows from inside the skin. When you feel hot, extra heat comes out through your skin. As a result, your body temperature drops.
    How do I move ?
    Muscles(肌肉) are found in most parts of your body. They work with your bones to help you move – whenever you cry or smile, eat or speak, walk or dance, etc.
    Why do I breathe ?
    Your body needs to take in oxygen from the air and give out the unwanted carbon dioxide in the body. When you breathe, air comes through your nose and mouth into your lungs(肺) where oxygen flows to different parts of your body.
    What makes me sneeze ?
    When dust or a strong smell gets into your nose, you sneeze. This is the way your body cleans up the dust in your nose. Your lungs push out the air and try to clear your nose.
    What does my heart do ?
    Your heart is a very special muscle. It is slightly bigger than your fist (拳头) and grows bigger as you do. If you place your hand on your heart, you will feel your heart beating which forces blood to move around your body.

    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).

    Lasers（激光） have many uses including improving someone's eyesight, playing DVDs, cutting the diamonds（钻石） and the list goes on and on. Now, there could be a new use for this powerful tool-changing the weather!

    The Swiss scientist Jean Pierre Wolf is working on using laser beams（激光束） to change the weather for the better. He wants to use it to help stop climate（气候） change. Sounds crazy, right? Well, there is already something kind of like it.

    Cloud seeding（云催化） is a way people stop rain from falling. It uses rockets to release chemicals into the atmosphere（大气层）, but it's not known what this might do to the environment. So Professor Wolf wants to find a better way to do this, and a laser is a good choice since the only thing it uses is light, not chemicals. But how would it work? According to CNN, it would make new clouds. The laser would make condensation（冷凝） happen, in other words producing drops of water. And then the water would turn into really small pieces of ice. Then clouds start to be made just naturally.

    Professor Wolf's hope is to help control the weather in places like California that can face both heavy floods and droughts（干旱）.They are also trying to use lasers to control lightning. Using lasers to change the weather has been tested in a lab, and they have been quite successful in some fields. They are still trying to find out how to use it in the real world, but it could be a new way to stop climate change. "Every time you think you have done everything you can with lasers, something new comes up," said Professor Wolf. "It's quite amazing."

    Caterpillars (毛虫) are often used as fish bait (鱼饵). However, the creatures may get a better life — they are now setto join the war on plastic wastes.

    Federica Bertocchini isa Spanish scientist. When she's not working in her lab, Bertocchini keeps bees.One day, when she looked at her hives(蜂箱), she found dozens of caterpillars called waxworms(蜡虫). These insects are often used to feed fish. In the wild, however,they live in beehives, feeding on the wax that bees use to build theirhoneycombs(蜂巢). Bertocchini picked out the caterpillarsand put them in a plastic bag. Surprisingly, when she returned to the bag aftercleaning out the hives, she found it full of holes. The worms had eaten theirway out.

    Bertocchini came up withan interesting question: Were the waxworms digesting(消化) the plastic? Then she got in touch with peersat the University of Cambridge, Paolo Bombelli and Christopher Howe. Accordingto their paper in Current Biology, some chemical or combination of chemicalswithin the insects can really break down plastics.

    Bertocchini and hercolleagues discovered that it took a waxworm about 12 hours to eat up amilligram of plastic shopping bag. However, the scientists warned that it wouldbe at least several years before they release(释放) waxworms into the environment. They want to know if the insectsare using the plastic as a food, or just because they want to escape. If theyjust want to escape, they are going to get fed up very soon. But if they'reusing it as an energy source, it's a completely different game. Anotherquestion lies in the insects' feces(粪便). If the fecesturn out to be poisonous, then there will be little point in pursuing(追究) the matter.

    "It's certainly notgoing to be the case that within six months we've solved the world's plasticproblem," said Howe. "l wouldn't want people to think that within afew months, they can start throwing away plastic bags without worrying aboutit."

    This is a street crossing. There are red and green lights at each corner. Drivers must watch the lights carefully.

    When there is a green light, the cars may go on. When there is a red light, the cars must stop.

    They must wait until the red light changes (变成)to green. Then they can go on. Sometimes the cars want to make a right turn or a left turn. They can make a right turn when the light is green or red. But they must wait until the green light is shining (闪亮) if they want to turn left. Some people are color-blind (色盲的). They can't see the difference (不同点) between red and green. These people mustn't drive, or there may be an accident (事故) .We must keep our street safe (安全的).