such a/an adj n和so adj a/an n的意思一樣，都表示“如此..."，它們的區別就在于such是形容詞，修飾的是后面的名詞或名詞詞組；而so是副詞，只能是用來修飾形容詞或副詞的。so還可以表示數量的形容詞，與many、few、much、little連用，形成固定搭配。

such a/an adj n和so adj a/an n的相關例句

1、Shanghai is such a big city==Shanghai is so big a city.

2、This is such an interesting book.== This is so interesting a book.

3、Such a good girl is she that we all like her.

4、Such a selfish man did Tom become that no one loved him any longer.

5、Such a wonderful sight did I watch last night.

6、It's so interesting a book that I have read it many times.
7、It's so heavy a box that I can't carry it .