A.15 B.20 C.25 D.30
A.材料實(shí)體、開口及閉口孔隙、顆粒間空隙 B.材料實(shí)體、開口孔隙、顆粒間空隙 C.顆粒間空隙、開口及閉口孔隙 D.材料實(shí)體、開口及閉口孔隙
A.2%~10% B.3%~6% C.4%~6% D.3%~12%