it is said that the people who have friends live longer than the people who don't的句子结构

问题描述:

it is said that the people who have friends live longer than the people who don't的句子结构
是什么从句

主句:it is said ,it 是形式主语.后面的that从句作真正的主语
主从作真正的主语:that the people (主语)+ who have friends (定从,修饰people)+ live (谓动)
+longer +(比较状从) than the people +(定从,修饰people) who don't.
句意:据说有朋友的人们活得比那些没有朋友的人们要长寿些