题目内容:
明挖爆破时,准备信号是( )。
A.鸣30s、停、鸣30s、停、鸣30s B.鸣20s、鸣10s、停、鸣20s、鸣10s、停、呜20s、鸣10s C.鸣10s、停、鸣10s、停、鸣10s D.鸣20s、停、鸣20s、停、呜20s
参考答案:
答案解析:
明挖爆破时,准备信号是( )。
A.鸣30s、停、鸣30s、停、鸣30s B.鸣20s、鸣10s、停、鸣20s、鸣10s、停、呜20s、鸣10s C.鸣10s、停、鸣10s、停、鸣10s D.鸣20s、停、鸣20s、停、呜20s