A.11kN/m3,13kN/m3 B.12kN/m3,14kN/m3 C.11kN/m3,14kN/m3 D.12kN/m3,15kN/m3
A.50 B.60 C.70 D.80
A.2.5 B.3 C.3.5 D.4