A.≤18kg/m3 B.≥250kg/m3 C.18~22kg/m D.180~250kg/m3
A.≤18kg/m3 B.≥250kg/m3 C.18~22kg/m3 D.180~250kg/m3
A.≤25cm2 B.25~100cm2 C.100~230cm2 D.25~230cm2