1/4单选题
难度：
1.
用轻绳连接并跨过定滑轮（不计滑轮的质量和摩擦），
悬于空中，
放在斜面上，均处于静止状态. 当用水平向左的恒力推时，
仍静止不动，则（ ）
用轻绳连接并跨过定滑轮（不计滑轮的质量和摩擦），悬于空中，放在斜面上，均处于静止状态. 当用水平向左的恒力推时，仍静止不动，则（ ） | A | 受到的摩擦力一定变小 |
| B | 受到的摩擦力一定变大 |
| C | 轻绳上的拉力一定变小 |
| D | 轻绳上的拉力一定不变 |
正确答案：RA==
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
如图所示，物体
、
和
叠放在水平桌面上，水平力
，
，分别作用于物体
、
、
分别表示
，
，
，
，
，
在力
作用下一起以相同的速度沿
所受的摩擦力，下列说法正确的是（ ） 
如图所示，
、
三个物体完全相同，且各接触面不光滑，现用水平力