Save the world's trees

    "When it comes tothe Earth, there is no time to waste." says the Earth Day Network. And that isright. Protecting our environment is very important, and World Earth Day wascreated in 1970 to ask more people to protect our environment. On April 22, peoplearound the world celebrate Earth Day.

Every year thereis a special topic, and this year it is "Trees for the Earth", so Earth Daythis year will be all about planting trees. They are planning to plant 7.8billion trees within the next five years.

That's a biggoal, and you might wonder why trees are so important. Because they can take incarbon dioxide (CO₂) and protect the air quality(质量). CO₂ isa chemical in our atmosphere, but humans make too much of it. Each person makesabout 2.3 tons a year, which is bad for the environment.

Well guess what!Planting new trees is important because people cut down a huge number of trees.Last year, there were 3 trillion trees in the world, about 139 billion inChina. But according to China Daily, the world's total number has been almostcut in half since human civilization(文明) began. That's because 15billion trees are cut down every year.

So we need toplant more to make up for（弥补）the ones we lost. One treecan take in 21. 8 kilograms of CO₂ per year. And it's still one ofthe cheapest and best ways to get rid of CO₂.

    But don't forget that we can also help the environment by cutting down on how much energy(能源) or water we useevery day. Every little thing helps.

根据短文内容，回答问题（1-4），英译汉（5）。

    Do you notice music playing there when you go somewhere? Today most stores, stations restaurants and other places play music. You might even hear music in an office or on a farm.

Scientists believe that music changes the way people behave. They think that Western classical music makes people feel rich. When a restaurant plays classical music, people spend more money on food and drinks. When the restaurant plays modern music, people spend less money. Without music, people spend even less.

Scientists also believe that loud, fast music makes people eat faster. In fact, people eat their food faster when the music gets faster. Some restaurants play fast music during their busy hours. This gets people to eat faster and leave more quickly. Restaurants can make more money this way.

Some scientists think that music makes people think and learn better. They say that music helps students be more active. It is true that people learn better when they are relaxed. And listening to music can help people relax.

    Next time you hear music somewhere, be careful. It might change the way you do things.

    Do you know how to make friends with a group of people? Let me tell you the steps about making friends with the group. Maybe it's helpful(有帮助的)to you.

    First, you need to know what kind of group they are. If people of the group are shy, never ask them “Why don't you talk?” “Why are you quiet?” or “Why do you look shy?”.They don't like such questions.

    Next, remember that each group is different. They may use different words, like different things or have different ways of “hanging out”.

    Then, the important thing is that you should try to be outgoing. If you are outgoing, you would become very popular. Remember, nobody wants to make friends with a shy person.

    Finally, find a right topic to talk with the group. For example, you can talk with them about the weather, the news, their hobbies or their school life.

根据短文内容，选择最佳选项。

    Is there intelligent(有智力的) life on other planets(行星)? For years, scientists said "No." or "We don't know." But today this is changing. Seth Shostak and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists somewhere in the universe. They also think we will soon contact these beings(人；生物).

    Why do Shostak and Barnett think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. "This is long enough for other planets to have intelligent life," say Shostak and Barnett. The second reason is size——the universe is huge. "Tools like the Hubble Telescope (哈勃望远镜) have shown that there are at least 100 billion galaxies (银河系) ," says Shostak. "And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be similar to Earth. "

    In the past, it was hard to look for signs of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to discover smaller planets--the size of Mars or Earth--in other solar systems (太阳系).These planets might have intelligent life.

    Have beings from space already visited Earth? "Probably not," says Shostak. "It's a long way away. However, intelligent beings may contact us in other way, such as radio signals(信号). "In fact, they may be trying to communicate with us now, but we don't have the right tools to receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other.

    Many people know that rubbish is a big problem on planet Earth. What many people don't know is that junk has become a problem in outer space too.

    According to BBC News, there are more than 22,000 pieces of space junk floating around the earth. And these are just the things that we can see from the surface of the earth by telescopes (望远镜). There are also millions of smaller pieces of junk that we can't see.

    Objects, like bits of old space rockets or satellites, move around the planet at very high speeds, so fast that even a very small piece can break important satellites or become dangerous to astronauts. If the smallest piece of junk crashed into a spaceship, it could damage it.

    To make things worse, when two objects in space crash, they break into many smaller pieces. For example, when a U.S. satellite hit an old Russian rocket in 2009, it broke into more than 2,000 pieces, increasing the amount of space junk.

    To reduce additional space junk, countries have agreed that all new space tools can only stay in space for 25 years at most. Each tool must be built to fall safely into the earth's atmosphere after that time. In the upper parts of the atmosphere, it will burn up.

    Many scientists are also suggesting different ways to clean up space junk. In England scientists are testing a metal net that can be fired into space junk. The net catches the junk and then pulls it into the earth's atmosphere to burn up. The Germans are building robots that can collect pieces of space junk and bring them back to Earth to be safely destroyed.

    "The problem is becoming more challenging because we're sending more objects into space to help people use their mobile phones and computers," says Marco Castronuovo, an Italian space researcher.

    "The time to act is now. The longer we leave the problem, the bigger it will become," he says.