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第三篇 Light Night, Dark Stars Thousands of people around the globe step outside to gaze at their night sky. On a clear night, with no clouds, moonlight, or artificial lights to block the view. people can see more than 14,000 stars in the sky, says Dennis Ward. an astronomer with the University Corporation for Atmospheric Research (UCAR) in Boulder. Colo. But when people are surrounded by city lights, he says, they’re lucky to see ISO stars. If you’ve ever driven toward a big city at night and seen its glow from a great distance, you’ve witnessed fight pollution. It occurs when light from streetlights, office buildings, signs, and other sources streams into space and illuminates the night sky. This haze of light makes many stars invisible to people on Earth. Even at night, big cities like New York glow from light pollution, making stargazing difficult. Dust and particles of pollution from factories and industries worsen the effects of light pollution. "If one city has a lot more light pollution than another." Ward says, "that city will suffer the effects of light pollution on a much greater scale." Hazy skies also make it far more difficult for astronomers to do their jobs. Cities are getting larger. Suburbs are growing in once dark. rural areas. Light from all this new development is increasingly obscuring the faint light given off by distant stars. And if scientists can’t locate these objects, they can’t learn more about them. Light pollution doesn’t only affect star visibility. It can harm wildlife too. It’s clear that artificial light can attract animals, making them go off course. There’s increasing evidence, for example, that migrating birds use sunsets and sunrises to help find their way, says Sydney Gauthreaux Jr., a scientist at Clemson University in South Carolina. "When light occurs at night," he says, "it has a very disruptive influence." Sometimes birds fly into lighted towers, high-rises, and cables from radio and television towers. Experts estimate that millions of birds die this way every year. Does the writer think growing cities affect astronomers’ work Why does he think so
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阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。 Captain Cook Arrow Legend It was a great legend while it lasted, but DNA testing has (51) ended a two-century-old story of the Hawaiian arrow carved from the bone of British explorer Captain James Cook (52) died in the Sandwich Islands in 1779. "There is (53) Cook in the Australian Museum," museum collection manager Jude Philip said not long ago in announcing the DNA evidence that the arrow was not made of Cook’s bone. But that will not stop the museum from continuing to display the arrow in its (54) "Uncovered: Treasures of the Australian Museum," which (55) include a feather cape presented to Cook by Hawaiian King Kalani ’opu’u in 1778. Cook was one of Britain’s great explorers and is credited with (56) the "Great South Land," (57) Australia, in 1770. He was clubbed to death in the Sandwich Islands, now Hawaii. The legend of Cook’s arrow began in 1824 (58) Hawah’an King Kamehameha on his. deathbed gave the arrow m William Adams, a London surgeon and relative of Cook’s wife, saying it was made of Cook’s bone after the fatal (59) with islanders. In the 1890s the arrow was given to the Australian Museum and the legend continued (60) it came face-to-face with science. DNA testing by laboratories in Australia and New Zealand revealed the arrow was not made of Cook’s bone but was more (61) made of animal bone, said Philp. However, Cook’s fans (62) to give up hope that one Cook legend will prove true and that part of his remains will still be uncovered, as they say there is evidence not all of Cook’s body was (63) at sea in 1779. "On this occasion technology has won," said Cliff Thornton, president of the Captain Cook Society, in a (64) from Britain. "But I am (65) that one of these days ...one of the Cook legends will prove to be true and it will happen one day."
论述题 在进行两个平均数差异的检验时，需要考察哪些因素。
论述题 简述影响信度的因素。
Hundreds of years ago, life was much harder than it is today. People didn’t have modern machines. There was no modern medicine, (41) . Life today has brought new (42) . The biggest one is pollution. (43) pollution has made our rivers and lakes dirty. It kills our fish and pollutes our drinking water. Noise pollution makes us talk louder and become angry (44) easily. Air pollution is the most serious kind of pollution. That’s bad to all (45) things in the world. Cars, planes and factories all pollute our air every day. (46) the polluted air is so thick that it is like a quilt(被子) over a city. This kind of quilt is called smog(烟雾). Many countries are making rules to (47) pollution. Factories must now clean their water before it is thrown away. They mustn’t blow dirty into the air. We need to do many (48) things. We can put waste things in the dustbin and not throw it on the ground. We can go to work by (49) bus or with our friends in the same car. If there are (50) people driving, there will be less pollution.
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