signal sorting

例句：

1. 1. The traffic policeman used his flashlight to signal thedriver to stop.
   交通警察用他的手电筒示意司机停车。
2. 2. Thenew sign was erectedat the entrance of the museum.
   博物馆入口处新立了一个标志牌。
3. 3.The beacon on the ship guidedthe lost sailors back to safety.
   船上的灯塔指引迷失的水手安全返回。