signal operation battalion

例句：

1. 1. The policemanused a flashlight to signal the driverto stop.
   警察用手电筒示意司机停车。
2. 2. The ship's flag isa symbol of national pride.
   船的旗帜是国家自豪的象征。
3. 3. The traffic light is acommon signal for pedestrians crossing the street.
   交通灯是行人过马路的常见信号。