题目

The elevator broke down and we were t inside it. 答案：【1】trapped如图所示的措施中，为了减小摩擦的是( )A. 机械表保养时上油B. 防滑垫表面做得凹凸不平C. 旋钮侧面制有条纹D. 轮胎上制有花纹