as的使用方法

Their grandfather was as jovial and sociable as their grandmother was quiet and withdrawn.

merriam-websters vocabulary builder里这句话如何理解，as as 作比较状语从句仿佛讲解不通

这种似于：Tom is as clever as John is stupid. 汤姆非常聪明，而约翰非常笨。

把聪明和笨的程度都按0-10分级。Tom 若是8分的聪明，约翰就是8分的笨。

这个句式实质表示的是二个人或事物的相反的性质或特点都达到非常高的程度。起对比有哪些用途。