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.

    There are many wetlands(湿地)in China and some of them have become the world's important wetlands. The Chinese Yellow Sea Wetlands are among them. They are in Yancheng, Jiangsu Province. They are home for many different kinds of birds and animals. The world's largest Milu Deer Nature Reserve(自然保护区) is in them. More than 700 milu deer live freely there. In winter you can see some red-crowned cranes in the Yellow Sea Wetlands though there are not many in the world.

It is not too hot nor too cold in the wetlands. There is a lot of rain and sunshine, too. They are really good places for wildlife. Offering food and home for some special kinds of animals and birds is not the only reason why we need to protect wetlands. Wetlands are important because they also prevent flood(洪水). But some people want to change the wetlands to make more farms and buildings. This means there will be less and less space for wildlife.

    Luckily, more and more people are beginning to realize the importance of wetlands and wildlife. Every year, on February 2nd, many activities are held to tell people more about wetlands.

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    There is good and bad news about the number of trees on out planet. The good news is that there are seven times more trees for everyone than we thought.

    A few years ago, scientists believed that the world bad 400 billion（十亿）trees. However, a new study from Yale University shows that there are around three trillion（万亿）trees. Thatmeans a three followed by 12 zeroes. That means there are about 420 trees for everyone in the world today.

    The bad news is that thousands of years ago, the earth had six trillion trees. Humans cut in half the number of trees on the planet. Take Europe for example, it was a large forest thousands of years ago. Now much of it is cities and towns. And another 15 billion trees are lost each year.

    Dr. Thomas Crowther is one of the scientists from Yale University. He said the new number of trees from their study would change nothing. " The study only shows we need to do more to protect our forests." He said.

We've talked about snails (蜗牛) and their slow move. But much of the time snails don't move at all. They're in their shells —sleeping .

    Hot sun will dry out a snail's body. So at the least sign of hot sun, a snail draws its body into its shell and closes the opening with a thin cover. Then it goes to sleep. A snail will die in a heavy rain. So whenever it rains, it goes inside its shell house and goes to sleep. A snail can sleep for as long as it needs to. It can take a short sleep. Or it can sleep for days at a time. And it spends all the winter months in its shell, asleep.

    In spring the snail wakes up. Its body, about three inches long, comes out of from the shell. When hungry, the snail looks for food. It can't see very well. Its eyes, at the ends of the top feelers are very weak. But its sense of smell is very strong. It helps the snail to the new greens. Then the snail's little mouth goes to work.

    A snail's mouth is no longer than the point of a pin(针). Yet it has 256,000 teeth! The teeth are so small that you can't see them. But they do their work. If you put a snail in a hard paper box, it will eat its way out. And if a snail wears out its teeth, it will grow new ones.

    Mostly, a snail looks for food at night .But on cloudy days it eats in the daytime. It eats all day long. A snail can go on eating for hours and never feel full.

    Imagine this. You come back from school and your robot housekeeper is already waiting for you at the door. He turns on the lights, air-conditioner and television. While you are having dinner, he cleans the floor. Before you go to sleep, he tells you the weather report, then reads you a bedtime story.

    Such thoughts are not just for stories. Now they can happen in the real world, as long as you have the robot Alpha 2. Alpha 2 was a star at the 2017 World Robot Conference(大会), which was held from August 23^rd to 27^th in Beijing. More than 150 universities and companies from across the world brought their robots to the event for show and sale. Some robots work in factories. Some robots go to outer space or under water for exploration. But the highlights(亮点)of the event were service robots.

    This kind of robot is the closest to our daily lives. From cleaning to teaching, music to sports, service robots have been used to do many kinds of jobs.

    Teo is a popular service robot, as well as an artist and music teacher. His 53 fingers help him play the piano well. He played John Lennon's song Imagine at the conference.

    There is another service robot called Bestic. It acts as a human arm to feed people with a spoon. It can be a good helper for little kids, the elderly and those with difficulties using their hands.

    The scientists believe that it may not be far when every family has at least one service robot.

    "Without music, life would be a mistake, "famous German philosopher(哲学家)Friedrich Nietzsche said over a century ago. Music is a big part of our lives. But in recent years, some American schools have cut music classes to control budgets(预算).

    For example, Chicago public schools hurt arts education when it fired over 1, 000 teachers. Among them, 10 percent of the teachers taught art or music, according to The Washington Times. In fact, this is not just a problem in the US. In other countries, such as China and the UK, music classes are not thought to be as important as ones like science, math and history. That's partly because music is not seen as a very important life skill, and it isn't tested. Many students are busy with schoolwork, so parents and students choose to focus on subjects that are tested more often.

    However, learning music is beneficial(有益的)in many ways.

    When playing music, you need different abilities to work together. It is not as simple as it looks, according to Kenneth K. Guilmartin of Music Together, an early childhood music development program. For example, when playing the piano, people see music notes and decode(解码)them in their brains. They also use their fingers to make sounds. You need to deal with all these things at the same time.

    Music has a special connection with science as well. You can see that many scientists are good at playing music：Einstein played the violin and German physicist Max Planck was talented in playing the piano.