英语so that 和so.that的用法,这句话里为什么用so that而不是so.that

英语so that 和so.that的用法,这句话里为什么用so that而不是so.that
I've always hated making mistakes or pronouncing a word incorrectly when I speak English,but Mrs Li just smiles,so that you don't feel competely stupid.

因为so that 连用 引导目的状语从句时,表示“以便；为了.而当so that前用逗号是,意思是“因此;所以”.so...that：so＋形容词或副词＋that ...引导结果状语从句.意思是“如此……以致于……”