A.50mm B.60mm C.100mm D.300mm
A.L≤2h且≤1000mm B.L≤2h且≤1500mm C.L≥2h且≥1500mm D.L≥2h且≥1000mm
A.強(qiáng)度高,剛度好,承載能力大 B.構(gòu)造簡單,施工方便 C.防火 D.耐久性能好