单项选择题
A.<1.0% B.<0.5% C.<1.5% D.<2.0%
A.0.3-0.5MPa B.0.4-0.5MPa C.0.5-0.7MPa D.>0.7MPa
A.≤4.5% B.≤5.0% C.≤4.0% D.≤3.5%