预测煤层突出危险性的单项指标值中,瓦斯放散初速度Δp≥()时,煤层有突出危险性。
A、5
B、7
C、10
参考答案:C
对有毒作业场所,要()监测,作业人员要定期进行体检。
A.定期
B.抽样
C.随机
In the figure above, what is the length of PQ times the length of RS (1) The length of PQ is 5. (2) The length of QR times the length of PR is equal to 12.