A.1000~1200kg/m3 B.1100~1300kg/m3 C.1200~1400kg/m3 D.1300~1500kg/m3
A.社會(huì)主義B.農(nóng)業(yè)社會(huì)C.科技社會(huì)D.經(jīng)濟(jì)社會(huì)