It was announced that only when the fire was under control __________to return to their homes.

A．the residents would be permitted

B．had the residents been permitted

C．would the residents be permitted

D．the residents had been permitted

（）能全面直观地反映建筑物内部整体构造关系、楼层分布、楼梯的构造、室内外地面高差、屋顶流水坡度。

A.剖面图

B.立面图

C.平面图

D.结构施工图