单项选择题
A.截止阀 B.止逆阀 C.球阀 D.安全阀
A.5%~30.5% B.5%~33.5% C.5%~36.5% D.5%~39.5%
A.10%~17% B.10%~15% C.5%~15% D.10%~20%