A.2.5g/cm3,900kg/m3,1500kg/m3 B.2.2g/cm3,1000kg/m3,2100kg/m3 C.4.2g/cm3,1200kg/m3,1700kg/m3 D.3.1g/cm3,900kg/m3,1500kg/m3
A.碳化收縮 B.濕脹干縮 C.化學(xué)減縮 D.干燥收縮
A.3 B.6 C.9 D.12