A.六级 B.七级 C.八级 D.九级
A.准轻质 B.一般轻质 C.混合轻质 D.超轻质
A.1.10~1.20 B.1.20~1.30 C.1.30~1.40 D.1.40~1.50
A.10% B.20% C.30% D.40%