单项选择题
A.≤0.25% B.≤0.15% C.0.25%—0.6% D.＞0.6%
A.≤0.35% B.≤0.25% C.≤0.45% D.＞0.6%
A.棉帆布 B.维纶帆布 C.聚酯帆布 D.钢丝绳芯