so修饰形容词，副词

例如 if you’re so stupid as to buy it..假如你笨到（如此地步以至于）去买这个东西。。。stupid 就是形容词


such修饰名词:

例如 if you're such a fool as to buy it ....意思同上。fool就是个名词。


意思都是，如此。。。以至于




然后这两个词组还有变形，so as to 和such as to，中间连一起不加其他成分，意思分别是

so as to: 为的是,以便
例句: He ran quickly so as to catch the last bus. 他跑得很快以便赶上那末班车。

such as to:达到这样的程度以致
例句: His speech is such as to incur enmity. 他的演说会引起别人的敌意。

such 指代前面的名词（即speech），so as to 中的so 不能代替名词，主要是修饰形容的和副词