signal flag

例句：

1. 1. The policeman waved the signal flag to alert other drivers.
   警察挥动信号旗来警告其他司机。
2. 2.The flag of the country is a symbol of its national pride.
   国家的旗帜是其民族自豪的象征。
3. 3. The flag was raised in honor of the fallen soldiers.
   为了纪念阵亡士兵，升起了国旗。