A.相對(duì)安裝 B.都向下安裝 C.背向安裝 D.都向上安裝
A.相鄰環(huán)搭口應(yīng)對(duì)齊 B.相鄰環(huán)搭口互相錯(cuò)開(kāi)60° C.相鄰環(huán)搭口互相錯(cuò)開(kāi)180° D.相鄰環(huán)搭口互相錯(cuò)開(kāi)90°