单项选择题
A.1个月 B.2个月 C.3个月 D.4个月
A.40% B.60% C.50% D.70%
A.日常维护 B.巡检 C.大修 D.计划维修
A.面积0.75m2,厚度为5mm B.面积0.6m2,厚度为3mm C.面积0.6m2,厚度为5mm D.面积0.75m2,厚度为3mm
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