- Do you know Victory Day in China?
- Yes, it's _______ September 3rd _______ each year. It tells the world that Chinese people love peace and hate wars. Chinese people will never forget the history.
下列搭配错误的是( )
如图所示,为一皮带传动装置,右轮半径为r,a为它边缘上一点;左侧是一轮轴,大轮半径为4r,小轮半径为2r,b点在小轮上,到小轮中心的距离为r。c点和d点分别位于小轮和大轮的边缘上。若传动过程中皮带不打滑,则( )①a点和b点的线速度大小相等 ②a点和b点的角速度大小相等 ③a点和c点的线速度大小相等 ④a点和d点的向心加速度大小相等
月面有圆缺的变化,月面貌本身 ____ (填“有”或“没有”)变化。