母乳的钙磷比例通常是（） A.1：1 B.2：1 C.3：1 D.1：2

直肠癌Dukes分期，不正确的是（）

A.D期：癌肿伴远处器官转移

B.B期：癌肿未超出浆肌层，伴淋巴结转移

C.C₂期：癌肿侵犯肠壁全层，伴肠系膜动脉根部淋巴结转移

D.C₁期：癌肿侵犯肠壁全层，伴肠旁系膜淋巴结转移

E.A期：癌肿未超出浆肌层，并且无淋巴结转移

推式技术的应用是（）。

A.查询信息

B.信息公告

C.下载软件

D.链接网站

根据《公司法》的规定，负责召集股份有限公司股东大会会议的是( )。

A．董事长
B．董事会
C．监事会
D．总经理

现代教育技术的发展经历了五个发展阶段，建构主义学习理论是（）引入现代教育技术领域。

A、初级发展阶段

B、迅速发展阶段

C、系统发展阶段

D、网络发展阶段

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.

The ball is easier to hold on to ______.

A．when friction is greater

B．when friction is less

C．when it is heavier

D．when it bounces strangely