A.离地高度1.0-1.2m B.离地高度0.5-0.6m C.承受外力3000N D.承受外力2000N E.承受外力1000N
A.0.3kN/m2 B.0.50kN/m2 C.1.10kN/m2 D.1.50kN/m2
A.6 B.8 C.10 D.12
A.50%~60% B.60%~70% C.70%~80% D.80%~90%
A.五级B.六级C.七级D.八级