理解正式语言和非正式语言之间的区别很重要。

It's important to understand the ___distinction between formal and informal language.

这两个哲学概念之间存在微妙的区别。

There's a subtle ___distinction between these two philosophical concepts.

一位好老师不会根据学生的背景而区别对待。

A good teacher makes no ___distinction based on a student's background.