单项选择题
A.无烟煤、烟煤、褐煤 B.无烟煤、烟煤、肥煤 C.无烟煤、烟煤、硬煤 D.无烟煤、烟煤
A.90%-98% B.90%-95% C.95%-98% D.85%-98%
A.90%-98%B.80%-98%C.75%-90%D.65%-75%
A.75%-90% B.65%-80% C.60%-75% D.50%-60%
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