多项选择题
A.降低摩擦 B.减缓摩擦 C.防止烧结 D.防止锈蚀
A.多环短侧链芳烃 B.多环短侧链环烷烃 C.少环长侧链环烷烃 D.多环芳烃
A.异构烷烃 B.多环芳烃 C.正构烷烃 D.少环长侧链环烷烃
A.螺杆与衬套内严重磨损 B.电机转数不够 C.动环与静环密封圈损坏 D.吸入管路堵塞或漏气
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