单项选择题
A.0.2 kPa B.0.4 kPa C.0.6 kPa D.0.8 kPa
A.0.3 kPa B.0.6 kPa C.0.9 kPa D.1.2 kPa
A.0.1% B.0.4% C.0.8% D.1.2%