单项选择题
A.24m B.50m C.100m D.120m
A.体积密度应不小于1.25g/cm3 B.体积密度应不小于1.5g/cm3 C.体积密度应不小于2.0g/cm3 D.体积密度应不小于2.30g/cm3
A.5m B.6m C.4m D.8m