![](https://static.youtibao.com/asksite/comm/h5/images/m_q_title.png)
[单选题]
掘进工作面附近 20 米范围内瓦斯浓度达到()时,或局部积聚瓦斯浓度达到()时,不得钻眼
A.1%,2%
B.1.5%,2%
C.1.5%,2.5%
![](https://static.youtibao.com/asksite/comm/h5/images/m_q_a.png)
A、1%,2%
![](https://static.youtibao.com/asksite/comm/h5/images/solist_ts.png)
A.1%,2%
B.1.5%,2%
C.1.5%,2.5%
A、1%,2%
A.2%,1.5%
B.1.5%,1%
C.1%,0.5%
D.2%,1%
采掘工作面爆破地点附近20 m以内风流中,瓦斯浓度达到()时,严禁爆破。
A.1.O%
B.1.5%
C.2.O%
A.下风流端20m
B.上风流端20m
C.上风流端10m下风流端20m
D.上风、下风流端各20m