高铁客专进站、出站信号机在点灯状态,列车头部压入信号机内方进路的第一区段时,信号机自动关闭;信号机内方进路的第一区段解锁后,该信号机自动转为灭灯状态。
参考答案:对
齿转啮合时的冲击引起机床()。
A、松动
B、振动
C、变动
D、转动
-What were you doing when I called you at 8 o'clock yesterday?
-I _________ the violin at that time.[ ]
A. play
B. is playing
C. played
D. was playing