单项选择题
A.先减压、再关阀 B.同时关阀减压 C.先关阀、再减压 D.不分先后
A.0.1 B.0.3 C.0.5 D.0.6
A.0.5~0.8 B.0.6~0.8 C.0.7~0.8 D.0.8~0.9