单项选择题
A.流程 B.手柄 C.阀门
A.18.5-20%;≤12ppm;≤36ppm B.19.5-21%;≤10ppm;≤35ppm C.19.8-21%;≤10ppm;≤36ppm D.19.5-23%;≤10ppm;≤36ppm
A.二级 B.一级 C.三级