It was only thirty years ago that the building industry felt confident enough to erect office blocks of steel and reinforced concrete that had more than a dozen floors.
建筑行业是从30年前才开始有信心建造超过12层楼高的钢筋混凝土结构的办公大楼。
2
To reduce the overall weight of the building, it used less concrete in the floors; that in turn enabled it to cut down on structural steel.
为了减少建筑的整体重量，它在楼层中使用了较少的混凝土；这反过来又减少了对结构钢的使用。
3
Building all these new turbines, solar panels, and other infrastructure would eat up plenty of steel, concrete, and other resources.