A.80 B.150 C.160 D.170
A.從兩端開(kāi)始向中間對(duì)稱 B.中間開(kāi)始向兩端對(duì)稱 C.從中間向兩端或從兩端向中間
A.防護(hù)支撐 B.非承重 C.承重