We are obliged to them because some of these languages have since vanished, as the peoples who spoke them died out or became assimilated and lost their native languages.
句子分析: 这是一个带原因状语从句、定语从句的复合句,其框架结构分析如下: 主句的主、谓、宾结构:We are obliged to them 我们感激他们 原因状语从句:because some of these languages have since vanished因为自此这些语言中的一部分消失了 定语从句:as the peoples who spoke them die d out or became assimilated and lost their native languages 因为讲它们的人灭亡了或同化了,并且丧失了自己的语言