关于there be的用法

Question

Along the way I developed one of the best approaches to learning tennis there is.上面的句子中，there is为何放在句末，看上去还有双谓语？请问这用法是什么？

Answer 1

Along the way I developed one of the best approaches to learning tennis（that） there is.

there is 修饰先行词 approaches，that省略。宾语从句

在路上，我发展了已经存在的学习网球的最好途径之一

Answer 2