以下两句话：This is my mother. 和 Amy is a friend of hers. 其中hers指的是my mother's. 请问这两句话可以合并成 This is my mother, of whose Amy is a friend. 吗？如果不行的话该如何合并呢？

   【答】of whose 可以引导定语从句。但是， 在从句中，关系代词 whose 只能作定语，后接名词。所以：

    This is my mother, of whose Amy is a friend. （错误）

   This is my mother, one of whose friends Amy is.(正确) 

又如：

    It is a book of rare value, many of whose pages are dog-eared. 这是一本珍本书，许多书页都翻得卷了角了。（摘自徐广联主编《大学英语语法》第五版讲座与测试,p.809）