Mike, together with his parents, went to a picnic （或：went on a picnic）yesterday.

考试还考“语法术语，语法名称”吗？“专四考试” 纯属没事找抽型的。

这个句子，用来设计“主谓一致” ，还是不错的。不是用来分析 together with his parents 的句子成分的。毫无意义，且没有定论！

我认为，这是语言表达多样化的体现：

Mike went to a picnic yesterday together with his parents.

Mike,together with his parents, went to a picnic yesterday.

两个句子中，都是介词短语作方式状语。何来的插入语？根本不符合插入语的定义！