A.250 B.200 C.150 D.100
A.1/20 B.1/15 C.1/10 D.1/5
A.水平對撐或斜撐 B.正交或斜交的平面桿系支撐 C.豎向斜撐 D.環(huán)形桿系或環(huán)形板系支撐