In nature, you may see many insects(昆虫) and animals of different colors. Have you ever wondered why?

    Locusts are super delicious food for birds, but it is not always an easy job for birds to catch them. It is neither because locusts are good jumpers or runners nor because they are smarter than their enemies. The reason is that the colors, of locusts change with the colors of crops(庄稼). When crops are young, locusts look green. But when autumn comes, locusts change to the yellow and brown color as crops do.

    Brown bears, tigers and other animals move quietly through forests. They can't be seen easily by their enemies. This is because they have colors similar to the trees. For the same reason, polar bears that live on a land of snow and ice are white. Butterflies and bees living among the flowers are colorful like flowers. Soil insects are mostly dark colored and they live under the soil(土壤)in a dark and wet environment. However, insects with colors different from plants can easily be found and eaten by others. So in order to survive, they have to hide themselves in the daytime and appear only at night.

    Have you ever noticed some even stranger acts? The ink fish in the sea can send out some very black ink when it faces danger. As the ink spreads over, its enemies will find themselves suddenly in a dark world. At the same time the ink fish immediately swims away. That is how it keeps itself safe though it is not strong at all.

Scientists say life will be very different in 2050.First,there will be no TV channels (频道) . People will choose a programme (节目) from a computer and watch it on the television. We will get information on the computers only.

   Second, water will be a big problem. In many places, people won't have water to drink.

Third, cars will use new and clean fuels and they will go very fast. There will be a computer in every car. And computers will control the cars and there won't be any accidents (事故) .

    There are many colours in nature. But do you know if a colour has weight? I think you'll say "no". But I am afraid you are wrong. If you don't believe, you may do a small experiment.

    First, put two objects with the same weight into two boxes. Then, cover the box. Third, wrap(包裹) one box with a red piece of paper, the other with a white piece of paper. OK. Now hold the boxes with your hand one by one. It is certain that you will think the red one is a little heavier. Why do you think so? A scientist found that different colours have different weight in a man's mind. So he did many tests and at last he got the result. That is to say, every colour has its own weight in our mind and their order(顺序) is the same. The heaviest colour is red, then blue, green, orange, yellow and white.

    The scientist told us that colours also have smell. Can you smell the colour? Of course not. Then why did the scientist say so? That is because every colour stands for a kind of light with a certain wavelength (波长). It reaches our brain(大脑) through sense organs(感觉器官).

    According to this discovery, scientists say that people accept the colours they like, and refuse the colours they hate. So your body and mind will be healthy by using the colors you like. Or you'll be nervous or even get ill. For example, if you stay in a room with red windows, wallpapers and furniture for two hours, you'll feel you have been there for four hours. But if the room is blue, you'll feel you have been there for only an hour. Another example, if a person walks out of a red room and into a blue room, his temperature will fall. That means our body temperature will change with different colours.