3.6 双重所有格
物主代词不可与 a, an, this, that, these, those, some, any, several, no, each, every, such, another, which等词一起前置，修饰一个名词，而必须用双重所有格。公式为：a, an, this, that +名词+of +名词性物主代词。例如：a friend of mine, each brother of his.