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问题 填空题

为了用注射器抽吸密封在药瓶中的药液，医生先向药液中注入一些空气，这样做的目的是______．

答案

抽吸密封在药瓶中的药液，因为药瓶是密封的，为免瓶内气压不足，故要先向药液中注入一些空气，这样做的目的是增大瓶中药液上方的压强，以便更顺利地“吸”取药液．

故本题答案为：增大瓶中药液上方的压强

综合

阅读材料，回答下列问题。（10分）

材料一：该图为世界能源消费构成比例变化图。

材料二：日本能源安全情况（1973年和2000年）

 1973年2000年
能源进口依赖率（%）89.481.0
石油消费比重（%）77.453.0
进口中东石油占进口石油比量（%）7982
材料三：中东的动荡局势和美国对中东石油的垄断使得日本开始重视从其他地区进口石油。日本如果能够铺设通往俄罗斯的石油管道，那么俄罗斯每天向日本出口100万桶石油，日本对中东石油的依赖度就可以降低到65%。

（1）从材料一可看出，30年后天然气的消费比重将超过石油，其最主要的原因是什么？（3分）

（2）材料三是日本国针对它的什么能源安全问题而作出的努力？（3分）

（3）结合材料二和材料三，从地理角度思考，我国可以从日本国能源安全情况的变化中得到哪些启示？（4分）
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单项选择题

In fall 2006, the National Basketball Association (NBA) started using basketballs made with synthetic, or man-made, material instead of leather. They made the change because they wanted every basketball they use to feel and bounce the same. Not all leather balls are exactly alike in weight or how they bounce, but the synthetic balls are.
However, some players complained right away that the new balls bounced differently and were actually harder to control than the leather ones.
Physics helped answer questions about why the new balls felt different. For example, the scientists studied friction, which in this case affects the ability of a player to hold onto a ball. "The greater the friction, the better it will stick to his hand," explains a scientist.
Tests on both wet and dry balls showed that while the synthetic ball was easier to hold onto when dry, it had less friction and became much harder to hold onto when wet. That’s because sweat stays on the surface of the synthetic balls but gets taken into the leather balls.
The scientists also tested bounce and found that the logo printed on the new balls made their surface uneven and caused them to bounce a little strangely compared with the leather balls.
In January, the NBA went back to using the leather balls. They aren’t perfect, but for now, that’s just the way the ball bounces.

Why were the synthetic balls expected to be used in NBA according to the text

A．Because they are easier to control.

B．Because they waste less material.

C．Because they look exactly alike.

D．Because they feel and bounce alike..
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