题干

如图所示,木块在推力F作用下,向右做匀速直线运动.下面说法正确的是()

A:依据推力F的作用效果,推力F沿竖直方向的分力为Fcosα

B:木块受到水平推力、竖直推力、重力、摩擦力四个力的作用

C:推力F与摩擦力的合力方向一定竖直向下

D:推力F与摩擦力的合力一定为零

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C

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