such a/an adj n和so adj a/an n的意思一样，都表示“如此..."，它们的区别就在于such是形容词，修饰的是后面的名词或名词词组；而so是副词，只能是用来修饰形容词或副词的。so还可以表示数量的形容词，与many、few、much、little连用，形成固定搭配。

such a/an adj n和so adj a/an n的相关例句

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 .