I am smart and healthy because I have some good habits. I love reading books very much. I think books are important for everyone. A book can tell us a lot, and we can learn a lot from it. I also like playing sports. In the p
在光滑的水平面上,质量为2kg的甲球以速度v0与乙球发生正碰,弹性碰撞后,乙球的动量减少了6kg•m/s,则碰后甲球的速度为()
图绘制的是水的温度和时间关系的曲线,其中能正确反映研究水沸腾过程中温度随时间变化关系的是( )
填上所缺的单词。
— How ____ you?
— I'm fine, thank you.
下列结构示意图中,化学性质相似的一组是( )