A.5 B.4 C.3 D.2
A.薄煤層≥85%,中厚煤層≥80%,厚煤層≥75% B.薄煤層≥75%,中厚煤層≥80%,厚煤層≥85% C.薄煤層≥97%,中厚煤層≥95%,厚煤層≥93% D.根據(jù)實(shí)際情況確定
A.煤層穩(wěn)定程度、頂?shù)装?、傾角 B.巖漿巖、陷落柱、斷層 C.斷層、褶皺和巖漿巖(陷落柱) D.斷層、陷落柱、瓦斯