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.

    Rainforests (热带雨林) cover six percent of the earth's surface (表面). There are rainforests in many parts of the world. About 75 percent of animals live in rainforests. There are many beautiful birds, insects and so on. Some of them live on the ground, some live under the ground and others live in the trees, over 30 meters from the ground. It is always hot in the rainforests and the ground is always wet. It is also very dark there.

    The rainforests are very important for us. We need them! The trees and other plants in the forest help to make the air clean. They also help to control (控制) the temperature.

    Unfortunately, in many places, the rainforests are in danger. For example, many years ago there was a large rainforest in Java, but now there is nothing. The same thing happens now in many other parts of the world. It's time to take action to save the rainforests. We can never imagine a world without rainforests. If rainforests disappeared from the earth, we wouldn't find any trees, flowers or fruits. What's more, we wouldn't get clean air, and we wouldn't find any animals. The worst result would be that we wouldn't find any humans.

    As space science develops, man has learnt more and more about space. Space is not only amazing but also dangerous. While working in space, spacemen are facing danger as well as success.

    Scientists have found out that the radiation is the greatest danger to spacemen in space. When spacemen are working in space, they are in danger of the radiation from the Sun and other stars, which is bad for their health.

    Space rubbish is also a great danger to spacemen. It's reported that there were 9,000 man-made things flying in space. About 30% of these are satellites, 10% are spaceships, and the rest space rubbish. A small piece of these can knock a spaceship window and cause some damage.

    Scientists are watching and reporting any possible danger all the time. They are working to deal with space rubbish. Although space is really dangerous, it interests many people on Earth. In the near future, it may become possible for people to spend a few days in a space hotel. We may even choose to leave the Earth and live in space in a few years. So we should do something to help improve the space environment.

    The kiwi lives only in New Zealand. It is a very strange bird because it can not fly.

    The kiwi is the same size as a chicken. It has no wings or tail. It doesn't have any feathers(羽毛)like other birds. It has two feet and each foot has four toes. Its mouth is very long.

    A kiwi likes to have a lot of trees around it. It sleeps during the day because the sunlight hurts its eyes.

    It can smell things with its nose. It is the only bird in the world that can smell things. The kiwi's eggs are very big. There are only a few kiwis in New Zealand now. People never see them. The government says that people can't kill kiwi. New Zealanders want their kiwis to live.

    There is a picture of a kiwi on New Zealand money. People from New Zealand are sometimes called kiwis.

Dear sir,

    I am doing a project(课题) at school about animals in danger. I think the situation all over the world is really terrible.

    Firstly, I feel so sorry for the giant panda. Pandas mainly live on bamboo. A panda can eat about half its body's weight(重量) of bamboo in 24 hours！That's a lot of bamboo. I think we should try to do more to stop cutting down their forests. We would be so sad if they disappear.

    Secondly, what we should try to protect more is the Chinese alligators(短吻鳄) . They live in some parts of eastern China. They live in freshwater rivers and lakes but the water in some places isn't clean enough for them to live in. It's really dirty in fact. The government should stop factories from polluting the lakes and rivers.

    If we protect these beautiful animals in China, more people may come to China to visit our beautiful country, especially to see the quieter areas in the country. Now most visitors just see the cities.

    I hope you will encourage(鼓励) more people to think about such an important subject.

Yours,

Huang Jing

    Nowadays, computers and Internets are playing an important part in our life. Some people even say they can't live without them. We usually need to set passwords (密码) when we use computers and Internet. But not all the passwords are safe. In order to keep our accounts (账户)and personal information safe, we must learn how to make safe passwords.

    How can you make your computer and Internet passwords safe? Experts have some advice for you. You'd better remember the advice and they are useful for you. Here are the suggestions.

    Firstly, make your password out of capital(大写) letters. If your password is made of capital letters, it will be difficult for others to get into your account. It only takes a hacker(黑客) 10 minutes to work out a six- letter password made of small letters. But the same password in capital letters takes 10 hours to work out.

    Secondly, add numbers or symbols to your passwords. It may be much safer. Sometimes such password is not easy to remember, but it is really safe.

    Thirdly, never use personal information for passwords and use different passwords for different accounts. Experts say that a user should change his or her passwords every 90 days. In this way, hacker won't guess your passwords.