单项选择题
A.1.9m B.2.0m C.1.8m D.1.7m
A.5% B.4% C.3% D.6%
A.20m B.15m C.10m D.30m
A.巷道一般失修率 B.巷道严重失修率 C.井巷占用率 D.巷道失修率
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