Many animals hide to stay alive. They hide in many ways. Some animals hide in leaves; some animals hide in snow. Usually their colors or shapes help protect them. It's hard to see an Arctic bear in snow. Its white fur helps protect it. Chameleons(变色龙) can hide by changing colors. Their skin turns the same color as what is around them. Some chameleons can change colors in five minutes.

    Many animals try to look bigger than they are to stay alive. Some animals can make other animals think they are very big. If they look very big, animals that are looking for food will run away. Bears can walk on two legs. They look very, very scary. Some animals will run away from them.

Many animals try to stay around other animals. This helps them stay alive. Zebras stay close together so that they can help each other look out of danger. Seeing many stripes at once can also confuse animals that want to eat them. Some birds stay in a circle, each toward a different direction. In this way they can also help each other stay alive by looking around for animals that many want to eat one of them.

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    Are you nervous? Maybe you should sit in a blue room. Are you always cold? Maybe you should sit in a room painted in a "warm colour" such as soft orange. Are you often sad? Maybe you should sit in a yellow room. Some researchers believe that colour has the power to influence our feelings. They believe that colours affect(影响)everyone in the same way.

    One study was in a workplace. The researchers painted heavy boxes white and light boxes black. They want to see how colour affected the workers' feelings. Which boxes do you think were more difficult to lift? The heavy white ones? No. The white boxes were heavier but they looked light. The researchers think that this is because light colours seem light.

    Another study was at school. Researchers at the University of Alberta in Edmonton, Canada, studied children with behaviour problems in their classroom. When the walls were brown and yellow, the children's heart rate went up and they were over-active. However, when the walls were dark blue, the children's heart rate was slower and the children were much calmer. If this is true, we can think carefully about the colours around them--not just in our homes, but also in offices, in schools, in hospitals, in gyms, in museums, in restaurants and even in prisons.

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    A plant is a living thing. It uses its many parts to grow from a small seed to a large plant. Each part helps the plant stay healthy. Plants also need sunlight to grow. They get light from the sun and minerals from the soil. These things help the plant stay alive and grow.

    Today there are robots working in factories. Some can help to build cars, and they do easy jobs over and over again. Few people will do such jobs in the future because they are boring, but robots will never get bored.

    Scientists are now trying to make robots look like people. Some robots in Japan can walk and dance. However, some scientists believe that it will be difficult to make them really think like people. For example, scientist James White thinks that robots will never be able to wake up and know where they are. But many scientists don't think so. They think that robots will even be able to talk in 25 to 50 years.

    Some scientists believe that there will be more robots in the future. These new robots will look very different. Some will look like people, and others might look like animals. In India, for example, scientists made robots that look like snakes. When buildings fall down with people inside, these snake robots can help look for people under the buildings. This was not possible 20 years ago, but computers and rockets also seemed impossible 100 years ago. We never know what will happen in the future!

    Do you know when Earth Day is? It is on April 22nd, and it began in the US in 1970. Earth Day in our country began in the 1990s. Earth Day is a good time for people to think about what they can do to make the Earth clean and beautiful, because now the environment on Earth is getting worse and worse. In fact, there are many things we can do to protect our Earth.

    Plant trees.

    Planting more trees helps to reduce greenhouse gases (温室气体), stop the earth from running away and provide homes for animals.

    Don't waste.

    Do not waste water. Use both sides of paper when you write. Turn off the light when you leave. Take your cup with you. Take your own shopping bags to the supermarket. Stop using the plastic bags. Don't use any disposable things. We should save energy.

    Don't throw rubbish in the streets.

    When rainwater washes over the rubbish, it becomes polluted. The polluted water flows into the rivers and seas.

    Ride your bike or take a bus.

    Too many cars pollute the air and waste energy.

    Remember: Every day is Earth Day.

    We should protect the Earth every day, not just on Earth Day. The Earth is our home. Let's do our best to make the Earth cleaner and more beautiful.

    There are many animals in danger, such as pandas, elephants, and South China tigers.

    The South China tiger is the smallest tiger in Asia. It is also one of the rarest tigers in the world. Scientists think that there might be a few South China tigers living in the wild, but they are still not sure about it.

    The South China tiger is special in its face, but it shares the height with the common tigers. In the past, the South China tigers lived in the forests. But today more than half of them are living in zoos. If there are not safe places for them, they will die out soon. Baby South China tigers need their mothers' milk in the first two months. The mother teaches her babies how to hunt.

    Scientists think that people should do something to protect the rare animals. If people take action together, these animals will have a better place to live in. We'll also live in a better world.