题目

从全校参加数学竞赛的学生的试卷中，抽取一个样本，考察竞赛的成绩分布，将样本分成组，绘成频率分布直方图，图中从左到右各小组的长方形的高之比为，最右边一组的频数是. （1）成绩落在哪个范围的人数最多？并求出该小组的频数、频率；（2）估计这次竞赛中，成绩高于分的学生占总人数的百分百.Us, night's meteor (流星) shower left many people in the community dissatisfied and demanding answers. According to Gabe Rothschild. Emerald Valley's mayor, people gathered in the suburbs of the city, carrying heavy telescopes, expecting to watch the brightly burning meteors passing through the sky What they found instead was a sky so brightened by the city's lights that it darkened the light of the meteors passing overhead. "My family was so frustrated." admitted town resident Daune Cosby.” We wanted to make this an unforgettable family outing, but it turned out to be a huge disappointment.” Astronomers—scientists who study stars and planets—have been complaining about this problem for decade, They say that light pollution prevents from seeing objects in the sky that they could see quite easily in the past. They call on people and the government to take measures to fight against it. There is yet a population besides professional and amateur star observers that suffers even more from light pollution. This population consist of birds, bats, frogs, snakes, etc. For example, outdoor lighting severely affects migrating(迁徙的) birds. According to the International Dark-Sky Association, “100 million birds a year throughout North America die in crashes with lighted buildings and towers.” Countless more animal casualties(伤亡) result from the use of artificial lighting. Clearly, people enjoy the benefits of lighting their evenings, but some scientists think it can be harmful to humans, too. They worry that exposure to light while sleeping can increase a person's chances of getting cancer. Emerald Valley is only one community that is becoming aware of the negative effects of light pollution. For years. Flagstaff, Arizona, has enforced lighting regulations in its city in order to assist astronomers at the Lowell Observatory. Similar efforts have been made worldwide, and a movement is underway to remind us to turn off lights when we are not using them, so that other creatures can share the night. 41. It happened last night that ______. A. the city's lights affected the meteor watching B. the meteors flew past before being noticed C. the city light show attracted many people D. the meteor watching ended up a social outing 42. What do the astronomers complain about? A. Meteor showers occur less often than before. B. Their observation equipment is in poor repair. C. Light pollution has remained unsolved for years. D. Their eyesight is failing due to artificial lighting 43. What is the author concerned about according to Paragraph 4? A. Birds may take other migration paths. B. Animals' living habits may change suddenly. C. Varieties of animals will become sharply reduced. D. Animals' survival is threatened by outdoor lighting. 44. Lighting regulations in Flagstaff. Arizona are put into effect to A. lessen the chance of getting cancer B. create an ideal observation condition C. ensure citizens a good sleep at night D. enable all creatures to live in harmony 45. What message does the author most want to give us? A. Saving wildlife is saving ourselves. B. Great efforts should be made to save energy. C. Human activities should be environmentally friendly. D. New equipment should be introduced for space study.