strength classes of structural timber的意思|示意

木材强度等级 strength classes of mortar 砂浆强度等级 strength classes of structural timber 木材强度等级 strength classes(grades of concrete 混凝土强度等级 ..

钢材强度等级 钢材强度等级 strength classes of structural steel; strength classes of structural timber 块体强度等级 strength classes of masonry units; strength classes of mortar ..