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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. According to the article, resources such as wind ______.
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Plants in DesertOnly special plants can survive the terrible climate of a desert, for these are regions where the annual range of the soil temperature can be over 75℃. Furthermore, during the summer there are few clouds in the sky to protect plants from the sun"s ray. Another problem is the fact that there are frequently strong winds that drive small, sharp particles of sand into the plants, tearing and damaging them. The most difficult problem for all forms of plant life, however, is the fact that the entire annual rainfall occurs during a few days or weeks in spring.Grasses and flowers in desert survive from one year to the next by existing through the long, hot, dry season in the form of seeds. These seeds remain inactive unless the right amount of rain falls. If no rain falls, or if insufficient rain falls, they wait until the next year, or even still the next. Another factor that helps these plants to survive is the fact that their life cycles are short. By the time the water from the spring rains disappears—just a few weeks after it falls—such plants no longer need any.The perennials (多年生植物) have special features that enable them to survive as plants for several years. Thus, nearly all desert perennials have extensive root systems below ground and a small shoot system above ground. The large root network enables the plant to absorb as much water as possible in short time. The small shoot system, on the other hand, considerably limits water loss by evaporation (蒸发).Another feature of many perennials is that after the rainy season they lose their leaves in preparation for the long, dry season, just as trees in wetter climates lose theirs in preparation for the winter. This reduces their water loss by evaporation during the dry season. Then, in next rainy season, they come fully alive once more, and grow new branches, leaves and flowers, just as the grasses and flowers in desert do. The theme of the second last paragraph is why the perennials can survive as plants for several years.
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. The author doesn"t suggest that ______.
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. Which of the following statements is true of wind power
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. Which is the country with the first commercial power station that makes use of ocean currents produced by tides
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