A:1个
B:2个
C:3个
D:4个
—____ is it?
— It's candy.
Liu Ying is as ___________ as her sister.
一 Who is that? — .
如图所示,半径为R,重为G的均匀球靠竖直墙放置,左下方有厚为0.5R的正方体木块,用水平推力F 推木块,使球离开地面并缓慢上升,若不计一切摩擦,对该过程进行分析,有( )