A.0.5m B.1.0m C.1.5m D.2.0m
A.從兩端開(kāi)始向中間對(duì)稱(chēng)B.中間開(kāi)始向兩端對(duì)稱(chēng)C.從中間向兩端或從兩端向中間D.由一端向另一端
A.防護(hù)支撐 B.非承重 C.承重 D.無(wú)具體規(guī)定