In any small country like England, with a growing population, there is always the danger that the wide, open areas will be built upon and their beauty destroyed.

在任何一个像英格兰这样小的国家里，由于人口的不断增长，总是存在着把广阔的空旷场所用来建屋造房而使其美景受到破坏的危险。

不解之处：

1）will be built upon 如何进行语法成分分析？ upon=on是介词，它的宾语是什么呢？

2）their beauty destroyed, 为什么不是被动语态，即their beauty will be destroyed 呢？

麻烦老师详细分析，谢谢！