单项选择题
货油泵的蒸汽清洗装置用于清洗: Ⅰ机械轴封; Ⅱ口环; Ⅲ轴承; Ⅳ叶轮, 正确的是()。
A.ⅠⅡ B.ⅡⅢ C.ⅡⅣ D.ⅠⅡⅢ
A.15%/12%~17% B.30%/20%~30% C.40%/50%~70% D.60%/30%~40%
A.2 B.4 C.5 D.10