在轨道车与接触网作业车运行中，司机、副司机呼唤应答时，单臂拢拳屈伸表示注意信号或要求注意。
1、正确正确
暂无解析
Robots, ___(become) increasingly prevalent in factories and industrial plants throughout the developed world, are programmed and engineered to perform industrial tasks without human intervention.
The group is made up of local___(music)who have been performing together for several years.
一质点在xy平面内运动，运动方程为r=2ti+(3t2+2)j，则该质点的运动轨迹是()
He blamed his poor performance_____jet lag
飞机以300m/s的速度水平飞行，该处地磁场的磁感应强度竖直分量为6.0×l0-8T，则长为50m机翼上的动生电动势大小为()
