A.定樁位 B.保護(hù)孔口 C.增加泥漿壓力 D.便于澆注
A.10d B.15d C.20d D.25d
A.一人依次施焊 B.一人對(duì)稱(chēng)施焊 C.兩人依次施焊 D.兩人對(duì)角同時(shí)對(duì)稱(chēng)施焊