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  3. In fall 2006, the National Basketball Association(NBA)started using basketballs made with synthetic, or man-made, material inste

In fall 2006, the National Basketball Association(NBA)started using basketballs made with synthetic, or man-made, material inste

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问题     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______.
选项 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
答案D
解析 在第四段第二句话“That’s because sweat stays on the surface of the syntheticballs but gets taken into the leather balls．”这句话中提到：球员在使用由皮革制成的篮球时，手上的汗水会被篮球的表面吸收，即篮球重量会增加，所以选项D表达观点正确。
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