Because when we looked at the four platforms around the site, one of which is an upgrade of the families' platform, we knew that these had to be moveable to respond to changing conditions, and the changing definition of what Ground Zero is.
因为当我们看到废墟周围的四个平台， 其中一个是从家属看台更新而来的， 所以我们考虑到这些必须可以移动， 来应对不停改变的环境， 和对于世贸废墟中心是什么的这种定义的改变。