A.≥閥座喉徑的1/4 B.≤閥座喉徑的1/4 C.閥座喉徑的1/20 D.≥閥座喉徑的1/2
A.1% B.2% C.3% D.4%
A.650mmHg B.650mmH2O C.100kPa D.20kPa