My uncle sang a few songs,my aunt _____ the piano to accompany him.用play

题目

My uncle sang a few songs,my aunt _____ the piano to accompany him.用play
这个是不是就是独立结构啊,还是什么其他的,反正搞不懂

答案

很明显是独立主格,有逗号,没有连词,两个主语不一致,是with +名词+现在分词的独立主格模式（with省略了）
就是这个状语从句的变形：
when My uncle sang a few songs,my aunt was palying the piano to accompany him.