【判断题】缺口造成应力集中,在单向拉伸情况下还会形成两向或三向应力。
【简答题】某采煤工作面抽采瓦斯量为5.2m 3 /min,回风瓦斯浓度0.5%,回风断面为8m 2 ,风速为2m/s,求该采煤面的瓦斯抽采率。
【单选题】The author came to be curious about the man beside him.
【单选题】当平均风速为12m/s,大气浓度预测采用( )。
【单选题】The author came to be curious about the man beside him .
【单选题】The author came to be curious about the man beside him.