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Renewable Energy SourcesToday petroleum provides around 40% of the world"s energy needs, mostly fuelling automobiles. Coal is still used, mostly in power stations, to cover one-quarter of our energy needs, but it is the least efficient, unhealthiest and most environmentally damaging fossil fuel. Natural gas reserves could plug (填补) some of the gap from oil, but reserves of that will not last into the 22nd century either. Most experts predict we will exhaust easily accessible reserves within 50 years. We could fast reach an energy crisis. We need to rapidly develop sustainable solutions to fuel our future. Less-polluting renewable energy sources offer a more practical long-term energy solution. They may benefit the world"s poor too. "Renewable" refers to the fact that these resources are not used faster than they can be replaced.The Chinese and Romans used watermills over 2,000 years ago. But the first hydroelectric dam was built in England in 1870. Hydroelectric power is now the most common form of renewable energy, supplying around 20% of world electricity. China"s Three Gorges Dam, which has just been completed, is the largest ever. At five times the size of the US"s Hoover Dam, its 26 turbines (涡轮机) will generate the equivalent energy of 18 coal-fired power stations. It will satisfy 3% of China"s entire electricity demand.In 2003, the first commercial power station to harness tidal currents in the open sea opened in Norway. It is designed like windmill, but others take the form of turbines.As prices fall, wind power has become the fastest growing type of electricity generation—quadrupling worldwide between 1999 and 2005. Modem wind farms consist of turbines that generate electricity. Though it will be more expensive, there is more than enough wind to provide the world"s entire energy needs. Wind farms come in onshore and offshore forms. They can often end up at spots of natural beauty, and are often unpopular with residents. And turbines are not totally benign—they can interfere with radar and leave a significant ecological footprint, altering climate and killing sea birds. Migrating birds may have more luck avoiding them. Scotland is building Europe"s largest wind farm, which will power 200,000 homes. The UK"s goal is to generate one-fifth of power from renewable sources, mainly wind, by 2020. But this may cause problems, because wind is unreliable. China"s Three Gorges Dam ______.
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The Biology of MusicHumans use music as a powerful way to communicate. It may also play an important role in love. But what is music, and how does it work its magic Science does not yet have all the answers.What are two things that make humans different from animals One is language, and the other is music. It is true that some animals can sing (and many birds sing better than a lot of people). However, the songs of animals, such as birds and whales, are very limited. It is also true that humans, not animals, have developed musical instruments.Music is strange stuff. It is clearly different from language. However, people can use music to communicate things—especially their emotions. When music is combined with speech in a song, it is a very powerful form of communication. But, biologically speaking, what is musicIf music is truly different from speech, then we should process music and language in different parts of the brain. The scientific evidence suggests that this is true.Sometimes people who suffer brain damage lose their ability to process language. However, they don"t automatically (自动地) lose their musical abilities. For example, Vissarion Shebalin, a Russian composer, had a stroke (中风) in 1953. It injured the left side of his brain. He could no longer speak or understand speech. He could, however, still compose music until his death ten years later. On the other hand, sometimes strokes cause people to lose their musical ability, but they can still speak and understand speech. This shows that the brain processes music and language separately.By studying the physical effects of music on the body, scientists have also learned a lot about how music influences the emotions. But why does music have such a strong effect on us That is a harder question to answer. Geoffrey Miller, a researcher at University College, London, thinks that music and love have a strong connection. Music requires special talent, practice, and "physical ability. That"s why it may be a way of showing your fitness to be someone"s mate. For example, singing in tune or playing a musical instrument requires fine muscular control. You also need a good memory to remember the notes (音符). And playing or singing those notes correctly suggests that your hearing is in excellent condition. Finally, when a man sings to the woman he loves (or vice versa), it may be a way of showing off.However, Miller"s theory still doesn"t explain why certain combinations of sounds influence our emotions so deeply. For scientists, this is clearly an area that needs further research. Music can NOT be used ______.
Earth Angels1 Joying Brescia was 8 years old when she noticed that cigarette butts (烟头) were littering her hometown beach in Isle of Palms, South Carolina. When she learned that it takes five years for the remains of a cigarette to disintegrate (解体), she decided to take action. Joying launched a "No Butts on the Beach" campaign. She raised money and awareness about the need to keep the beaches clean. With the help of others, Joying also bought or received donations of gallon-size plastic ice-cream buckets. The buckets were filled with sand, and placed at all public-access areas of the beach. The buckets allowed people to dispose of their cigarettes before hitting the beach. Two years later, Joying says the buckets are full and the beach is nearly free of cigarette debris (残片).2 People who live in or visit Steamboat Springs, Colorado, have Carter Dunham to thank for a new state wildlife refuge that preserves 20 acres of marshland and many species of wildlife. Carter and other students wrote a management plan for the area around the Yampa River. The plan was part of a class project when Carter was a freshman at Steamboat Springs High School. Working with the Colorado Division of Wildlife, Carter and his classmates mapped the area and species of animals living there. They also made decisions about, among other things, where fences and parking areas should be built.3 Barbara Brown and her friends collect oil. It started as a project for their 4H Club after one of the girls noticed her father using motor oil to kill weeds on their farm in Victoria, Texas. They did some research and discovered that oil can contaminate ground water—a real danger, in rural areas, where people live off the water on their land. The girls researched ways to recycle oil and worked with a local oil-recycling company on the issue. Now, the "Don"t Be Crude" program runs oil-collection sites—tanks that hold up to 460 gallons—where people in the community can dispose of their oil.4 Five years ago, 11-year-old Ryan Hreljac was a little boy with a big dream for all the people in Africa to have clean drinking water. His dream began in the first grade when he learned that people were dying because they didn"t have clean water, and that as little as $70 could build a well. "We really take water for granted," says Ryan, of Kemptville, Ontario, in Canada. "In other countries, you have to plan for it." Ryan earned the first $70 by doing extra chores (零工), but with the help of others, he has since raised hundreds of thousands of dollars. His efforts led to the start of the Ryan"s Well Foundation, which raises money for clean water and health-related services for people in African countries and developing countries. Paragraph 2 ______
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My legs trembled with fear.
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