答案:D
The bike is very old, _______ he likes it very much.[ ]
A. and
B. but
C. so
D. or
如图质量为m=5千克的物体,置于倾角为θ=30°的粗糙斜面上.用一平行于斜面向上的大小为30牛顿的力推物体,使其沿斜面向上匀速运动,斜面始终静止于地面,求地面对斜面M的静摩擦力是多少?(g取10米/秒2)