The panda is _____ milk. [ ]
A. drinking
B. drink
C. drinks
D. eating
答案:A
大气边界层
某矿矿井总进风量为9800m3/min。井下各地点的实际用风量总和为8550m3/min,该矿井的有效风量率是多少?()
A.0.9
B.0.8724
C.0.8225
D.0.75