单选题
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 (天文学家) 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 150 stars.
If you"ve ever driven toward a big city at night and seen its glow from a great distance, you"ve witnessed light pollution. It occurs when light from streetlights, office (照亮) the night buildings, signs, and other sources streams into space and illuminates sky. This haze (朦胧) 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 (使变模糊) the faint (微弱的)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 (迁徙) 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 (破坏性的) 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.
单选题 On a clear night, people can see ______.
【正确答案】 D
【答案解析】本题问的是在一个晴朗的夜晚，人们可以看到什么。原文第一段的第二句话明确说到，“On a clear night, …people can see more than 14,000 stars in the sky”在没有云，没有月光，没有人造光源的晴朗的夜晚，人们可以看见14,000颗星星。由此可知，本题的正确答案为D。
单选题 Light pollution occurs when ______.
【正确答案】 A
【答案解析】本题问的是什么情况下会发生光污染。原文第二段的第二句话明确说到，“It occurs when light from streetlights, office the night buildings, …and illuminates sky.”由此可知，当路灯照亮……并照明天空时就发生了光污染。可见，A选项符合原文内容。因此，本题的正确答案为A。
单选题 Nowadays even suburbs are becoming unsuitable for scientists to do their jobs because ______.
【正确答案】 B
【答案解析】的是现在即使是郊区也不适合科学家的研究工作的原因。原文第五段的第二、三句话说到，“Suklurbs are growing in once dark, rural areas. Light from all this new development is increasingly obscuring the faint light given off by distant stars.”随着城市规模的扩大，曾经黑灯瞎火的乡村逐渐变成了市郊，那里的灯火使科学家无法观测到星体发出的微弱光芒。由此可知，本题的正确答案为B。
单选题 How does light pollution affect wildlife?
【正确答案】 B
【答案解析】本题问的是光污染会对野生动物产生什么影响。原文第六段的第三句话明确说到，“It"s clear that artificial light can attract animals, making them go off course.”人造光源会误导动物而致使它们迷路。由此可知，本题的正确答案为B。
单选题 The title "Light Night, Dark Stars" means ______.
【正确答案】 D
【答案解析】本题问的是标题“Light Night，Dark Stars”的意思。根据全文内容可知，本文主要介绍的是城市夜晚的灯光造成的光污染及其影响，其中一个影响就是使得星星都黯然失色。故本文标题的意思为“城市灯火通明的夜晚使星星失去光泽”。因此，本题的正确答案为D。