A.27,1780 B.27,1852 C.25,2000 D.26,1924
A.封闭的孔隙 B.粗大开口的孔隙 C.孔隙率大、具有微细、联通、开口的孔隙 D.粗大封闭的孔隙
A.5%~8% B.5%~10% C.10%~15% D.10%~20%