信号

例句：

1. 1.The policeman waved his hand to signal the driver to stop.
   警察挥动手示意司机停车。
2. 2. The traffic light is a signal for crossing the road.
   交通灯是过马路的信号。
3. 3. The new sign at the entrance of the museum is a good signal for visitors.
   博物馆入口的新标志对游客来说是一个很好的指示。