单项选择题
A.先进后退,5cmB.先退后进,5cmC.先进后退,6cmD.先退后进,6cm
A.砌体B.门窗过梁C.碇三角块D.空调洞预制块
A.140-160mm,45°~60°B.160-200mm,45°~60°C.140-160mm,35°~45°D.160-200mm,30°~45°