A.3m; B.5m; C.8m; D.10m
A.交通量; B.車輛類型; C.公路等級; D.橋梁類型
A.通航跨徑; B.標(biāo)準(zhǔn)跨徑; C.計算跨徑; D.經(jīng)濟跨徑