根据短文理解，选择正确答案。

    Imagine the situation. You are driving along a desert or on a mountain. You have no idea where you are. You passed the last house two hours ago. Then your car breaks down. It is night and it is cold. You have no mobile phone. What do you do? Well, next time take a GPS with you. This invention may be able to help you. It is a device(装置) which uses satellites (卫星) to find the user's position(位置). It can find your position to within 20 metres. A GPS cannot start your car, but at least you will know where you are.

    GPS, which means Global Positioning System, is a small radio receiver. It looks like a mobile phone. You can hold it in your hand, or put in your pocket. It is sometimes put into a watch or a telephone. We also find GPS devices in cars, planes, or boats. Some of these devices have electronic maps, so you know where you are. For example, in a city they can tell you the name of the street.

    There are three parts to the Global Positioning System. The first part is the receiver. You can hold it in your hand, or have it fixed into your car, plane, etc. The second part is a group of satellites orbiting the Earth. The receiver contacts at least four of the satellites and calculates(计算) its position. The third part of the system is a network of ground stations. They are all over the world. They control the satellites and make sure they are working well.

    Some people think that in the future the GPS will be as common as the mobile. They are becoming cheaper and more and more accurate(精确的). There are also new uses for the GPS. Perhaps they will become like watches. Everyone will have one and you will never be lost again.

A

    Air pollution is one of the most common types of pollution in the world nowadays. It is quite serious in many places, especially in big cities. It can do great harm to our environment such as making the earth warmer, causing acid rain or destroying the ozone layer. As for human beings, air pollution causes all kinds of breathing problems.

    There are several reasons for air pollution. Firstly, many cities have a lot of factories and there we need to make food, clothing and other things. Every year these factories pour millions of tons of smog into air. Secondly, power factories can also give out harmful air. For example, in 1986 there was a bad accident at a nuclear power station in Russia. A cloud of radiation crossed the whole Europe. It is said that 125,000 people died in Russia as a result of illnesses caused by this accident. Thirdly, there are more cars in cities now. Once they are out in the streets, they will take in fresh air and give out dirty gas. Besides, smoking cigarettes also makes air pollution worse as will as damaging(损害) our health.  

    Let me tell you something about sharks. Sharks are among the oldest animals in the world. There are over three hundred and fifty different kinds of sharks in the world. Most sharks are about two meters long and live in the seas.

    A shark can smell something in the water, for example, the blood of animals. That helps them find their food. Sharks mainly eat fish, other sharks and plants in the sea.

    Most sharks bite people by mistake. They think a person is a large sea animal. When the sun goes down or comes up, sharks are looking for food. So at these times people shouldn't go swimming in the sea.

    Today people kill sharks for food and their skin. The number of sharks in the world is dropping fast.

    "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.

Teaching kids gently

Students discuss whether it is right for strangers to educate others' kids. 

Recently, during a flight, a toddler (刚学走路的小孩) kept crying, and two strangers took her to the bathroom and locked her in there for "education". This led to a heated discussion. Examples like South Korea's "no-kids zones (区域)" and reminders (提示语) for parents on high-speed trains show how the public reacts to crying children. How do you feel about strangers "educating" noisy young children?

I think it's not OK for strangers to educate the children of others. Sometimes, children can be naughty and might shout in public. This can be annoying and make us want to step in. But from the child's point of view, a stranger stepping in and shouting at them can be scary. It can also hurt children's feelings. Parents can also feel stressed when their children disturb (打扰) other passengers, but they might not know what to do. Sometimes children cry to draw others' attention because they can't express their needs well. So as strangers, it's best to kindly remind parents to look after their kids and check if they are hungry or unwell. 

Cui Luoyao, 14, Beijing

Instead of strangers, parents should be the ones teaching their children how to behave properly. I believe many passengers "dislike children" not because of the children's behavior, but because they really can't stand their parents' attitude. As children grow up, it is normal for them to make mistakes and disturb others without meaning to because they are too small to understand so much information. What is really scary is that parents turn a blind eye to their children's mistakes, use "he is just a kid" as an excuse and force others to tolerate (容忍) their children. If a child really does something that disturbs others, then the parents should say sorry and solve the problem. 

He Liyan, 14, Jiangsu

 For the past years, Tokitae has been one of the biggest stars at the Miami Seaquarium(迈阿密水族馆). The blue whale has brought much fun to generations of Americans with her giant jump. Now, finally, people decided to release the whale to her" home waters. "

 The decision came after years of efforts from animal lovers. An animal from the ocean, these people say, should not be kept in a seaquarium. Blue whales are known to stay with their birth families for their whole lives. Tokitae's skin becomes infected(感染) after such a long time in an aquarium. And because she is sometimes fed fish that go bad, the whale has also picked up some other illnesses. Tokitae stopped working last year because of her health problems. 

 Tokitae's sad story began in the calm waters of Whidbey Island, in 1970. Men made a group of blue whales get together. They separated the mothers from their babies. Many of these whales died during this process, and more than fifty were kept at the Miami Seaquarium. One of these baby whales was Tokitae. 

 Tokitae's family are still alive, including the 90-year-old whale believed to be her mother. But scientists are afraid that if Tokitae were to meet her family, she would infect her illnesses to the other whales. There are also worries about her ability to travel across the United States to a new, wild environment. The whale, after all, is already 57 years old and is not in excellent condition. And she will need to be taught how to catch fish again.