A.8%~10% B.10%~12% C.12%~15% D.15%~18
A.絲炭暗煤亮煤鏡煤 B.鏡煤亮煤暗煤絲炭 C.亮煤暗煤鏡煤絲炭 D.鏡煤暗煤絲炭亮煤
A.0.25㎜~0.5㎜ B.0.12㎜~0.25㎜ C.0.1㎜~0.12㎜ D.0.074㎜~0.1㎜