signal bronze

例句：

1. 1. The traffic policeman used his flashlight to signal the driver to slow down.
   交通警察用他的手电筒示意司机减速。
2. 2. The new sign at the entrance of the museum is a reminder of its history.
   博物馆入口处的新标志提醒人们它的过去。
3. 3. The pilot signaled for assistance when he saw the plane in trouble.
   当飞行员看到飞机出故障时，他发出了求救信号。