帮我分析一下这个句子的语法成分

题目

帮我分析一下这个句子的语法成分
Considering how recent these developments are,it is even more remarkable that as long age as the 1960s,an Englishman,Leon Bagrit,was able to predict some of the uses of computers which we know today.
这句话中一定要详细的分析一下it is even more remarkable that as long age as the 1960s这个分句的成分和结构 尤其是that后面这个状语为什么要用that引导?把that去了不行吗?
还用Considering是不是引导的伴随状语?
提出的问题一定都要回答啊!

答案

considering现在分词作状语,主句是it is even more remarkable ,it 是形式主语,真正的主语是that后面一直到句末的从句.而这个从句里又有从句.（呃……楼主是不是打错了个单词,应该是as long ago as 吧,是一副词短语...