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问题 选择题

在大陆西岸，长年受该纬度带盛行风和30°附近 的气压带交替影响的气候类型是

A．地中海气候

B．温带大陆性气候

C．温带季风气候

D．温带海洋性气候

答案

答案：A

30°附近 的气压带是副热带高压，该纬度带盛行风是盛行西方；受副热带高压与盛行西方交替控制的是地中海气候。选择A项。

单项选择题 A1型题

连接单核苷酸组成核酸的是（）

A.共价键

B.氢键

C.高能键

D.磷酸二酯键

E.肽键
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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.

It can be inferred from the text that ______.

A．a synthetic ball takes in water faster than a leather ball

B．a leather ball is more difficult to make than a synthetic one

C．a synthetic ball is more expensive than a leather ball

D．a leather ball may increase its weight during a game
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