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、鸣20s、鸣10s
C 鸣10s、停、鸣10s、停、鸣10s
D 鸣20s、停、鸣20s、停、鸣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、鸣20s、鸣10s
C 鸣10s、停、鸣10s、停、鸣10s
D 鸣20s、停、鸣20s、停、鸣20s