such 是形容詞，修飾名詞或名詞詞組，so是副詞，只能修飾形容詞或副詞。so 還可與表示數量的形容詞many，few，much， little連用，形成固定搭配。

so + adj. such + a(n) + n.

so + adj. + a(n) + n. such + n. (pl.)

so + adj. + n. (pl.) such +n. (pl.)

so + adj. + n. (不可數)such +n.(不可數)

so foolish such a fool

so nice a flower such a nice flower

so many/ few flowers such nice flowers

so much/ little money. such rapid progress

so many people such a lot of people

so many 已成固定搭配，a lot of 雖相當于 many，但 a lot of 為名詞性的，只能用such搭配。so…that與such…that之間的轉換即為 so與such之間的轉換。