Forget the old idea that conserving energy is a form of self-denial—riding bicycles.

题目

Forget the old idea that conserving energy is a form of self-denial—riding bicycles.
问：Forget the old idea that conserving energy is a form of self-denial—riding bicycles
中：that conserving energy是一个什么结构?修饰什么成分?
和后边是搭配成定语从句的，先回答的就给分！

答案

是一个定语从句啊 修饰the old idea,来说明the old idea的内容是什么