单项选择题
A.≤0.05MPaB.≤0.10MPaC.≤0.20MPaD.≤0.25MPa
A.≤2(O2,mg/l)B.≤3(O2,mg/l)C.≤6(O2,mg/l)D.≤7(O2,mg/l)
A.≤7B.≤10C.≤30D.≤100