题干

双曲线C:
x
2
a
2
-
y
2
b
2
=1a>0,b>0
的右焦点为Fc,0,以原点为圆心,c为半径的圆与双曲线在第二象限的交点为A,若此圆在A点处的切线的斜率为
3
3
,则双曲线C的离心率为(   )

A:3+1

B:6

C:23

D:2

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答案(点此获取答案解析)

A

同类题2

阅读理解

    Scientists today are making greater effort to study ocean currents (洋流) . Most do it using satellites and other high-tech equipment. However, ocean expert Curtis Ebbesmeyer does it in a special way -- by studying movements of random floating garbage. A scientist with many years' experience, he started this type of research in the early 1990s when he heard about hundreds of athletic shoes washing up on the shores of the northwest coast of the United States. There were so many shoes that people were setting up swap meets to try and match left and right shoes to sell or wear.

    Ebbesmeyer found out in his researches that the shoes — about 60,000 in total — fell into the ocean in a shipping accident. He phoned the shoe company and asked if they wanted the shoes back. As expected, the company told him that they didn't. Ebbesmeyer realized this could be a great experiment. If he learned when and where the shoes went into the water and tracked where they landed, he could learn a lot about the patterns of ocean currents.

    The Pacific Northwest is one of the world's best areas for beachcombing(海滩搜寻) because winds and currents join here, and as a result, there is a group of serious beachcombers in the area. Ebbesmeyer got to know a lot of them and asked for their help in collecting information about where the shoes landed. In a year he collected reliable information on 1, 600 shoes. With this data, he and a colleague were able to test and improve a computer program designed to model ocean currents, and publish the findings of their study.

    As the result of his work, Ebbesmeyer has become known as the scientist to call with questions about any unusual objects found floating in the ocean. He has even started an association of beachcombers and ocean experts, with 500 subscribers from West Africa to New Zealand. They have recorded all lost objects ranging from potatoes to golf gloves.

同类题4

阅读材料,回答问题

材料一:从接受康有为的学说开始,梁启超的理想便是改革封建王朝,使之变成君主立宪制的资产阶级的国家。1899-1903的激进,与当时的国内政治形势密切相关,由于戊戌变法的失败和清政府的顽固保守,梁启超转而接受的孙中山的激进方案。1905年他的政治态度复归保守,重新鼓吹起改良与立宪。在袁世凯复辟帝制的关键时刻,梁启超却又拒绝诱惑,不怕威胁,坚决维护民主共和。

——摘编自杜先菊《梁启超政治思想的变化》

材料二:孙中山说,欲救亡图存,“革命为唯一法门”。即认为不推翻清王朝,中国决无生存于竞争世界的希望……共和制度是当今世界上最好的制度,中国应当取法乎上,直接建立共和制度,“方才是人类的进步”。还提出,中国可以借鉴外国经验教训,“举政治革命、社会革命毕其功于一役”。

——摘自汤奇学《孙中山的社会进化思述评》

材料三:1938年,***在党的六届六中全会上作的题为《论新阶段》的政治报告中最先提出了“马克思主义中国化”这个命题。他指出:“没有抽象的马克思主义,只有具体的马克思主义。所谓具体的马克思主义,就是通过民族形式的马克思主义,就是把马克思主义应用到中国具体环境的具体斗争中去,而不是抽象地应用它。成为伟大中华民族之一部分而与这个民族血肉相联的共产党员,离开中国特点来谈马克思主义,只是抽象的空洞的马克思主义。”

——摘编自姚中国《论***对马克思主义中国化的历史贡献》