Beacon towers are built at certain intervals to give the alarm if enemies approach.

每隔一定距离，就建一个烽火台，敌人接近时，发出警报。

youdao

Beacon towers are built at certain intervals to give the alarm if enemies approach.

每隔一定距离，就建一个烽火台，敌人接近时，发出警报。

youdao