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 know fish come out of eggs when they are born? After the little fish comes out of the egg, it eats the food in the egg. When it is big, it leaves the egg. It swims in the water. You can see the eyes and nose. Its ears are hidden in the head.

    Spree fish eat other fish. Some fish have small mouths and teeth and they often eat plants.

    Pollution inside homes and other buildings kills more than 4 million people each year．Many people die as a result of breathing smoke or from cooking over wood﹣powered of coal﹣powered stoves．

    One way to reduce the number of deaths is through cooking equipment powered by the sun．Crosby Menzies，a solar power expert in a South African company，described his latest solar cooker called the“Sol.4”，”It is four square meters of mirrors，six to eight meters in length．It is quite a large cooler．”

    The“Sol.4”works by reflecting （反射）light from the sun off large mirrors．The mirrors direct （把…对准）the light at a cooking pan．Then the light heats the pan with solar energy．Within two minutes，the pan is hot enough to cook sausages and onions．In just four minutes，water can be boiled．That is as fast as cooking with natural gas or electricity．

    The cooker is also much“friendlier”than other models because people do not have to stand in the sun to use it．And people can prepare meals without having to collect firewood or spend money on coal．Suchindividualswould be less likely to have breathing illnesses from harmful smoke．

    At present，the cooker only works when the sun is shining．But engineers are working on a way to make it work without sunlight．

    Each cooker costs about $2000，which is a large amount of money for most Africans．To solve that problem，Crosby Menzies has crated a non﹣governmental organization called solar Cookers for Africa．It plans to raise money through donations to provide poor people with solar cooking equipment．

    Every living thing on Earth is either a plant or an animal, right? Wrong! Many organisms（有机体）in our world are neither. Some of them float through the air, and some lie hidden in the ground. They do not need sunlight to survive, and if the weather becomes too cold, they can become inactive until conditions improve.

    What are these? They are called fungi(菌类), and you see them almost every day. Many kinds of fungi seem disgusting, such as the green black things that appear on the food which are left too long in the refrigerator. But other kinds are not so bad. For example, the yeast that is used to make bread and mushrooms (蘑菇) are both fungi.

    What makes fungi different from plants and animals? An animal can move around by itself. Fungi get around too, but they don't have feet, wings, or tails. They have to wait for wind or some other outside force to move them. Plants are different from fungi because they have chlorophyll（叶绿素）. It helps them make food from the energy in sunlight. Fungi do not have chlorophyll.

    Some fungi are bad, while others are not. Some fungi cause diseases, such as athlete's foot, which makes feet uncomfortable. Other kinds of fungi can be used to make medicines, which have saved many lives.

    Fungi clean up more than wounds, though. They are the world's first recyclers. Without fungi, our world would be a mess. Since fungi cannot make their own food as plants do, they must get their food elsewhere. Many fungi get their food from dead plants. They break them down and turn them into soil. The fungi get a meal, and the world gets a housecleaning.

    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.