湖南长沙有哪些县:请问这个句子该怎么分析，谢谢

why is it ? 主句
that 引导it的同位语从句
从句中：
some nations 是主语， often …others 形容词结构作some nations 的定语，
remain centuries free and independent 是从句谓语，保持几个世纪的自由和独立，
in spite of great wars that have been fought around them
that have been fought around them 是wars 的定语从句，
in spite of great wars 介词短语作状语，不管周围发生多么大的战争。

why is it that ...是强调句型：到底为什么会......
如：why is it that she cried?
她到底为什么哭？
often small in population and power when compare with others 定语相当于 which are often small in population and power when compare with others 起补充说明作用。
that have been fought around them定语从句，修饰wars
整句为：尽管周围战争不断，一些比起来人口少，力量小的国家，到底为什么会几个世纪保持自由独立呢？

不是插入语，而是后置定语
nations which are often small in population and power when they are compared to others
Why is it that 的that后面引导表语从句。
that have been fought around them是宾语从句。

often small in population and power when compare with others 修饰前面的nations
Why is it that some nations remain centuries free and independent in spite of great wars that have been fought around them 是句子的主干