A.300mm B.150mm C.200mm D.450mm
A.45°~60° B.40°~60° C.30°~45° D.根據(jù)架體的縱、橫間距確定
A.4~8m,4~8m B.5~10m,2~3m C.6~9m,2~3m D.6~9m,3~4m