A.0.3%~0.5% B.0.5%~1.0% C.1.0%~1.2% D.1.2%~1.5%
A.10 B.20 C.30 D.50
A.預(yù)制鋼筋混凝土欄板 B.金屬欄桿 C.砌體欄板 D.實(shí)心欄板