每日钉一下（低估买入高估卖出，为何说起来容易做起来难？）

Group 1 - The article highlights that most investors are familiar with stock index funds but have limited knowledge about bond index funds and their investment strategies [1]. - A free course is offered to educate investors on how to invest in bond index funds [1][2]. - Additional resources such as course notes and mind maps are available to enhance learning efficiency [2].