单项选择题
A.≤530℃ B.≤540℃ C.≤550℃ D.≤560℃
A.≤10Mg/l B.≤18Mg/l C.≤8Mg/l D.≤15Mg/l
A.0.12% B.0.1% C.0.04% D.0.15%