更多“函数f（x)=arctgx在[-1，1]上的平均值为____”相关的问题
接地导线应具有良好的导电性,其截面积不得小于15m㎡（）
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"Dancing Beijing" serves as the city’s foremost appearance. It is an image that show...What ideal does the character "Jing" in "Dancing Beijing" reflect
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市场调研可以采用问卷调研、陌生拜访、图书馆网络调研等多种方法。
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Why don"t birds get lost on their long flights from one place to anotherScientists have puzzled over this question for a long time. Now they"re starting to fill in the blanks. Not long ago, experiments showed that birds use the sun to guide them during daylight hours. How do birds fly at night Tests with artificial stars have proved that certain night-flying birds are able to follow the stars in their long-distance flights. A dove had spent its lifetime in a cage and had never flown under a natural sky. But it had an inborn ability to use the stars for guidance. The bird"s cage was placed under an artificial star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the artificial stars caused a change in the direction of his flight. But the stars are apparently their main means of navigation. When the stars are hidden by clouds, they apparently find their way by such landmarks as river courses, mountain ranges, coast lines. But when it"s too dark to see these things, the doves circle helplessly, unable to find their way.
Why don"t birds get lost on their long flights from one place to anotherScientists have puzzled over this question for a long time. Now they"re starting to fill in the blanks.
Not long ago, experiments showed that birds use the sun to guide them during daylight hours. How do birds fly at night Tests with artificial stars have proved that certain night-flying birds are able to follow the stars in their long-distance flights.
A dove had spent its lifetime in a cage and had never flown under a natural sky. But it had an inborn ability to use the stars for guidance. The bird"s cage was placed under an artificial star-filled sky. The bird tried to fly in the same direction as that taken by his outdoor cousins. Any change in the position of the artificial stars caused a change in the direction of his flight.
But the stars are apparently their main means of navigation. When the stars are hidden by clouds, they apparently find their way by such landmarks as river courses, mountain ranges, coast lines. But when it"s too dark to see these things, the doves circle helplessly, unable to find their way.
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根据《城镇燃气设计规范》，向CNG储配站和CNG瓶组供气站运送CNG的气瓶车和气瓶组，在充装温度为20℃时，充装压力不应大于()表压。
A.18MPaB.19MPaC.20MPaD.25Mpa
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体现“培土生金”治法的方剂是（ ）。
A. B. C. D. E.
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当电气火灾发生时，如果无法切断电源，就只能带电灭火，并选择干粉或者二氧化碳灭火器，尽量少用水基式灭火器。
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新环保法规定：未达到国家环境质量标准的重点区域、流域的有关地方人民政府，应当制定限期达标规划，并采取措施（）。
A.按期达标
B.努力达标
C.改善环境质量
D.减轻污染程度
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A．喘急胸闷，伴有咳嗽B．喘急气促，甚则鼻翼煽动C．喘咳痰多而黏，咯出不爽D．喘促、呼多吸少，动则更甚E．喘促短气，言语无力肺虚型喘证的临床表现是
A．
B．
C．
D．
E．
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杜甫的名句“出师未捷身先死”指的是诸葛亮。
A.对 B.错
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开立外债专用账户，银行应审核以下哪些项目？
A.外汇管理局核发的“国家外汇管理局资本项目外汇业务核准件”的要项是否为“账户开立” B.外汇管理局核发的《外债登记证》是否有效 C.外债借款合同上的要素与《外债登记证》是否相符 D.国家外汇管理局核准发放的《国家外汇管理局开立外汇账户批准书》
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简述细胞学说的建立过程及主要内容，并说明为什么说细胞学说的真正完善是1858年。
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