单项选择题
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
A.10cm B.20cm C.8cm D.15cm