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问题 选择题

以下情况中，可将物体看成质点的是（　　）

A．对某位学生骑车姿势进行生理学分析

B．计算子弹穿过一张薄纸的时间

C．研究“神舟六号”绕地球飞行

D．对于汽车的后轮，在研究其转动情况时

答案

A、对某位学生骑车姿势进行生理学分析，看的是姿势，所以不能看成质点，A项错误；

B、计算子弹穿过一张薄纸的时间，需要考虑子弹的大小，所以不能看作质点，B项错误；

C、研究“神舟六号”绕地球飞行，飞船相对到地球的距离小的多，所以飞船可以看作质点，C项正确；

D、对于汽车的后轮，在研究其转动情况时，需要考虑转动轴心，所以不能看作质点，故D项错误．

故选：C．

单项选择题

Questions from 36 to 40 are based on the following passage: China’s trade volume surged in 2010. The development wasn’t only in quantity, but also in quality — namely structure diversification.The European Union, the United States and Japan remained China’s top 3 largest trading partners in 2010.But trade volumes between China and other emerging economies increased also. Bilateral trade volumes between China and other BRIC nations — Brazil, Russia and India — all jumped more than 40 percent. That made India China’s tenth largest trading partner.Huang Guohua, Statistics Department Director of General Administration of Customs said “Trade volume between China and emerging economies increased faster than that with the traditional market. It indicates that China’s foreign trade is diversifying, and showing less dependence on the traditional partners. It’s a good way to reduce risks.”Data also shows that foreign trade volumes developed dramatically in China’s middle and western areas last year. Although the southern province of Guangdong still topped others in the total volume of import and export.Huang Guohua said “The export volume of middle and western areas surged over 40 percent year on year in 2010. The speed was 10 percentage points higher than the country’s total. It indicates that industrial structure has improved in these areas.”The import and export volume of private enterprises surged faster than the country’s average in 2010, with 47 percent year on year growth. Experts say China’s foreign trade development reduced dependence on foreign-funded enterprises.2010 imports and exports reached a historical high with a p sign that the country’s trade sector has shrugged off the global economic recession.

In which terms can we say that China’s foreign trade is diversifying（）

A．the development in quantity

B．the development in quality

C．the development in quantity and quality

D．the development in quotient
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单项选择题

立式轴流转桨式水轮机动作试验时，转轮接力器动作应平稳，开启和关闭的最低油压一般不超过工作压力的（）%。

A.5

B.10

C.15

D.50
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