____ ____
如图所示,一质量为m的物体,沿倾角为θ的光滑固定斜面由静止下滑,当它在竖直方向下落了h高度时,求重力的瞬时功率和整个过程中重力的平均功率.
Does she often____(play) football on Sunday?
--It is said that it was invented