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问题 选择题

如图所示，行星A绕 O点沿逆时针方向做匀速圆周运动，周期为，行星B绕 O点沿顺时针方向做匀速圆周运动，周期为.某时刻AO、BO刚好垂直，从此时刻算起，经多长时间它们第一次相距最远（   ）

A．

B．

C．

D．

答案

答案：A

题目分析:设经过时间两卫星相距最远（此时两卫星和中心天体在一条直线向且两卫星在异侧），则转过的角度之和为，即，解得，则B、C、D均错误，选项A正确。故选A。

听力题

“For those who haven’t been to Tibet, Tibet is a dream; for those who have a   1   been there, Tibet is a remembrance（记忆）.” said Li Wan, a graduate from Zhongshan University. “To local Tibetans, Tibet is a way of life. But to me, l   2 there is my life-time goal.”

Ms. Li suddenly showed her strong i   3   in Tibet after having worked in a company for less than three months. Since 1998, Li has spent most of her time in a war that is a challenge(挑战) to her life—she has got to almost every c   4  of Tibet within 8 years.

Li’s first trip to Tibet was only out of her loving freedom. She entered Tibet a   5  the Yunnan-Tibetan road. Although she couldn’t speak a word of Tibetan l  6  , this did not really stop her from t____7____ with local people. “To me, they are free, happy and c   8   to nature. It a   9   to me that people should live in this way, singing while working, dancing while living,” Li said.

Li described Tibet in words and photos. “My goal in the n   10   ten years is to make a good documentary.” said Li.

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单项选择题

西方人性理论中经济人假设来源于（）

A.享乐主义哲学观

B.霍桑实验

C.马斯洛的理论

D.薛恩的考察
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