题目

He __________ baseball. A . don't play B . doesn't plays C . doesn't play D . don't plays 答案：C如图所示，物体自倾角为θ的固定斜面顶端沿水平方向抛出后落在斜面上，物体与斜面接触时速度与水平方向的夹角φ满足：A. tanφ=sinθB. tanφ=cosθC. tanφ=tanθD. tanφ=2tanθ