单项选择题
A.煤、矸石、夹矸煤和硫铁矿 B.矸石、夹矸煤 C.矸石 D.夹矸煤
A.±1％ B.±1.2％ C.±1.5％ D.±2.0％
A.6 B.16 C.18 D.20
A.1% B.10% C.20% D.12%
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