单项选择题
A.30s;40s B.25s;30s C.30s;35s
A.20° B.25° C.30° D.35°
A.飞溅润滑 B.机油泵式润滑 C.滴油润滑 D.手动润滑
A.可燃蒸气 B.空气 C.氧气 D.可燃粉尘
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