When some plates(板块)of the Earth move suddenly, an earthquake happens. Many earthquakes begin under the sea. Earthquakes may happen anywhere on the Earth. They often happen near the mountains.

    During an earthquake, the shakings make rocks rise suddenly and even crack(断裂) open. Houses fall down. People are killed or hurt, and sometimes the whole villages or cities are destroyed.

    Can we do something to keep ourselves safe from earthquakes? Scientists have studied earthquakes and made maps that show the “earthquake belt（带）”. In area of these belts, it's possible for earthquakes to happen. In these areas we should build strong houses to fight against earthquakes.

    In the future, Scientists will be able to tell when and where an earthquake will attack before it happens. They can also tell people what to do and how to deal with it.

    Coloring is an activity that children worldwide have long enjoyed. With a picture already made for them, kids simply chose a crayon, pencil or marker of their favorite color and fill it in. Today, it also becomes more and more popular among teenagers and even adults, who are enjoying relaxing hours of coloring. In December, five of the top ten best-selling books in the United States were coloring books.

    They are fun, but are coloring books good for you?

    The good feedback(反馈)from customers is encouraging. Trina Lucida, a popular artist creating coloring books, says that many of her customers are buying the coloring books for others who are sick or going through a hard time. She adds that the "big idea" behind her latest book is to encourage people to do something creative.

    Lucida is right, according to Allan Rohan, a psychology(心理学)professor. "Many customers think of coloring books as a new creative stage," he said in an interview, "but what's more important is that people spend time coloring in order to reduce stress after a long day." Research shows that coloring can reduce stress by guiding people to focus on(专注)one simple task. When a person is filling in a flower with a light purple color, he focuses on the flower and forgets about all his troubles in life.

    Experts add that coloring may relieve a certain kind of pain. Doing the coloring helps people relax their mind and calm down. Also, coloring helps people's brain in a healthy way. The shape of the drawing makes one side of the brain active, while the color of the drawing improves the other. Coloring can bring out your imagination and take you back to your childhood. Interesting, isn't it?

    "It's very relaxing," said Susan Jackson, a big fan of Lucida's coloring books. "Coloring frees my mind. And it's not just to try to fill blank(空白的)pages. The pictures make me happy and there is just something about them. So I'm saving the pictures I like best to the very end."

    Rubbish is a major kind of environmental pollution. Each person produces about 2kg of rubbish a day. We are making waste products faster than nature can break them down. And we are using up resources(资源)faster than they can he replaced(取代).

    This adds up to trouble for the environment. Where does all that rubbish go? What can be done to help dispose of(处理)rubbish? How can we make less rubbish?

    Rubbish isn't just the smelly rotting fruits, vegetables or meat that we throw away(抛弃) in our homes Those are only a small part of all tile stuff we throw away. We create other kinds of waste, in construction, mining and in our factories.

    Did you ever wonder what happens to your rubbish? Most is burned(燃烧)or buried in landfills(垃圾填埋场). Less than a quarter of our waste is recycled(回收).

    With a population of 1.3 billion(十亿), rubbish is a big problem for China. Chinese city create around 148 million tons of rubbish every year. The amount is growing at around 10 percent each year.

    Once we used about 3 billion plastic shopping bags everyday in China. The result was a great waste of resources and serious pollution. So we did something about that. Now we use more cloth bags and shopping baskets when we shop.

    In the coming years China will build waste-to-energy plants in cities to clean up the rubbish. But there's a lot more that needs to be done. And you can play a role.

    In 1969, humans landed on the moon for the first time. Now, many other countries want to go there as well. Why?

    The moon has a lot of minerals (矿物质) and other useful things. We want to find out if we can use them. The moon is our closest neighbor in space. We can use it as a rest station. Then, we can learn more about other planets far away in space.

    The moon is 3,474 kilometers in diameter (直径). It is about one-fourth the size of Earth. If Earth is the size of a basketball, the moon is the size of a tennis ball.

    The moon has much less gravity than Earth. If you can jump 1.5 meters on Earth, you can jump 9 meters on the moon.

    The moon is very quiet. There is no sound there. There are a lot of grey rocks on it. The moon's sky is always black.

    Our moon is about 384,400 kilometers away from Earth. The total length of the Great Wall is about 21,200 kilometers. We would have to put about ____ Great Walls end to end to reach the moon!