Mr. Liu has two sons. One is a doctor, and _______ is a driver. A. other B. another C. the other D. others 答案:C2.哈尔滨第24届世界大学生冬运会某滑雪道为曲线轨道,滑雪道长s=2.5×103m,竖直高度h=720m.运动员从该滑道顶端由静止开始滑下,经t=200s到达滑雪道底端时速度v=30m/s,人和滑雪板的总质量m=80kg,取g=10m/s2,求人和滑雪板:(1)在滑动过程中重力做功的功率;(2)在滑动到底端时,重力的功率.