单项选择题
A.手工定时润滑 B.压力供油润滑 C.溅油润滑 D.油雾润滑
A.0.6% B.2.11% C.10% D.12%
A.是低合金钢 B.平均含碳量为40% C.Cr含量小于0.1% D.是碳钢
A.10% B.5% C.2.11% D.0.25%
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