题目

一篇英语阅读题
In fall 2006,the National Basketball Association (NBA) started using basketballs mad with synthetic,or man-mad,material instead of leather（皮革）.They made the change because they wanted every basketball they use to feel and bounce（弹起）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（摩擦力）,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.
Test 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（汗水）stays on the surface of the

提问时间：2021-03-04

答案

虽然慢了,但是保证准确!1.D依据：They made the change because they wanted every basketball they use to feel and bounce（弹起）the same.Not all leather balls are exactly alike in weight or how they bounc...