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.50%~90% B.50%~80% C.80%~90% D.80%~95%
A.20~30mm B.50~100mm C.60~80mm D.40~50mm