2009 Tianjin Question 1 Single-choice Differentiating 2009_天津 Paper 1.(6分)物块静止在固定的斜面上,分别按图示的方向对物块施加大小相等的力F,施力后物块仍然静止,则物块所受的静摩擦力增大的是( ) A. 垂直于斜面向上B. 垂直于斜面向下C. 竖直向上D. 竖直向下 Answer keyD ☆ SaveCan't do it, show the explanation查看原卷 →