一、单选题 1.下列说法中正确的是 A.静止在水平面上的物体对支持物的压力就是它的重力B.用弹簧竖直悬挂静止的小球,小球对弹簧的拉力就是小球的重力 C.静止在水平面上的物体所受的支持力和压力互相平衡D.摩擦力的方向可以与运动方向相同,可以与运动方向相反,也可以与运动方向 First, the single-topic questions 1. The following statement is correct A. The object is still resting on a horizontal surface of the pressure on the support is its gravity B. With the spring hanging vertical ball vertically, the small ball on the spring tension is small Gravity ball C. static objects in the horizontal plane subject to the support and pressure balance D. the direction of friction with the same direction of movement can be opposite the direction of movement can also be the direction of movement