A.1309kN B.1400kN C.1500kN D.1600kN
A.680 B.750 C.450 D.560
A.750 B.800 C.850 D.950
A.5250kN B.5260kN C.5270kN D.5956kN
A.50mm B.100mm C.150mm D.应计算后确定