阅读理解。

   Your brain controls everything you do. It makes it possible for you to think,

Learn, create and feel; to blink(眨眼) and breathe and for your heart to heat –this fantastic control center is your brain. It is so amazing that a famous scientist once called it "the most complex(复杂) thing we have yet discovered in our universe".

Can this small grey organ(器官) , which weighs less than one and a half kilos, really do so much? Amazingly , your brain contains about 100 billion neurons(神经元) -it would take you over 3, 000 years to count them all. Believe it or not, the activity in your brain never stops. Your neurons create and send more messages than all the phones in the world. And although one neuron creates only a little electricity, all your neurons together can produce enough electricity to power a light bulb (灯泡).

    So exactly how fast does your brain work? Well, imagine this: a bee lands on your foot. Neurons in your skin send this information to your brain at a speed of more than 240 kilometers per hour. Your brain then uses other neurons to send the message back to your foot to shake the bee off quickly. These neurons can send this information at more than 320 kilometers per hour. No computer has your brain's unbelievable ability to deal with the amount of information coming from your eyes, ears and other sensory organs.

    But how does your brain allow you to learn things that you will use in the future? The structure (结构) of your brain changes every time you have a new thought, remember or learn something. For example, riding a bike seems impossible at first, but soon you are able to do it. How? As you practice, your brain sends "bike riding" messages again and again soon, the actions are learnt and you are able to ride a bike easily from then on.

   Do you want to live another 100 years or more? Some experts say that scientific advances will one day enable humans to last tens of years beyond what is now seen as the natural limit of the human life span.

    “I think we are knocking at the door of immortality(永生),” said Michael Zeya, a Montclair State University business professor and author of two books on the future. “I think by 2075 we will see it and that's a conservative estimate(保守的估计).”

    At the conference in San Francisco, Donald Luria, a professor at New Jersey Medical School in Newark said advances in using genes as well as nanotechnology(纳米技术) make it likely that humans will live in the future beyond what has been possible in the past. “There is a great push so that people can live from 120 to 180 years,” he said. “Some have suggested that there is no limit and that people could live to 200 or 300 or 500 years.”

    However, many scientists who study in ageing are doubtful about it and say the human body is just not designed to last past about 120 years. Even with healthier lifestyles and less disease, they say failure of the brain and organs will finally lead all humans to death.

    Scientists also differ on what kind of life the super aged might live. “It remains to be seen if you pass 120, you know; could you be healthy enough to have good quality of life?” said Leonard Pooh, director of the University of Georgia Gerontology Centre. “At present people who could get to that point are not in good health at all.”

    Many animals are in danger of dying out. We can see the number of animal species decreases faster and faster and this trend will continue. From 1980 to 2010, at least I million animal species disappeared. Worse still, more and more wild animals are in great danger. It is not a piece of terrible news; it is a fact, a harsh reality. Unfortunately, we may not see these animals in the near future.

    Why is the number of animal species declining year by year? Apparently animals have become victims of fashion industry. Animal skin has been used to make fashionable clothes and these clothes are sold at a high price. So some greedy people begin to kill animals in a large quantity.  This irresponsible behaviour not only breaks the balance of nature but also endangers the living environment of human beings.

    As far as I am concerned, something must be done to stop this illegal action. We believe "no buying, no killing". First, we must make concerning laws to protect these animals in danger.  Second, we must take some measures to protect animals effectively. Animals are our friends and part of our environment. Third, we should raise people's awareness to protect animals and our environment.  In this way, we can build a harmonious society and ensure a sustainable development.

    Did you know that each day one person in the USA throws away 4.4 pounds of rubbish? Almost every month, we throw away our own rubbish in packaging alone. Packaging (including boxes, bags, etc.) comes to our homes with the things we have bought. Several weeks ago, the TV news said that in a city in Italy tons of rubbish were piled up in the streets, and the smell was rather terrible. What can we do to help? We should get to know the following Rs.

    Reduce To reduce means to make less rubbish. That is one of the first things we all should do for the environment. Reduce your rubbish by doing things like packing your lunch in reusable containers(可再利用的容器), taking smaller portions(份) at dinner so you don't waste food when you have had enough, writing on both sides of paper, and using less water when taking a shower.

    Reuse to reuse is to use things again. Think about the bags you get from the shop. They can be reused to carry your lunch, to hold your rubbish, or to collect used cans. You can even take them back to the school next time to carry your things instead of getting a new bag!

    Recycle(回收利用) Recycling is an important part of keeping our planet clean and green. It can also save energy. Be sure that you don't throw things in the rubbish bins that can be recycled to make something else Paper, plastic, cans and bottles can all be recycled. But food, electrical waste and mobile phones cant. When you are not sure whether something can be recycled, go to your parents and teachers for advice.

Follow the three Rs, and every one of us can do something to save the Earth. It is also the best way to save ourselves.