A:20°
B:40°
C:60°
D:80°
He was told ____ (drive) carefully.
写出反义词
妙不可言—____ 粗心—____ 眼前—____
如图所示,一箱苹果沿着倾角为θ的斜面,以速度v匀速下滑.在箱子的中央有一个质量为m的苹果,它受到周围苹果对它的作用力的方向( )