Mike came to ask me for some advice on (how to learn Chinese

状语,因为如何学中文,是方式状语.
但是如果把on也加入括号内,那么on how to learn Chinese就是修饰前面some advice的了,
我们知道,修饰名词或名词短语的叫定语,所以加了on就是后置定语.