题目

3．（08年黑龙江鹤岗）在日常生活和生产活动中，有时要增大摩擦力，有时又要设法减小摩擦力，下列四个实例中属于减小摩擦力的是    (    )      答案：DThis was just the first stage of the robot design challenge, the finals _____ for 2015.A. will be set B. being setC. set D. having set