“You”（你/你们）是第二人称代词。

"You" is ___the ___second ___person pronoun.

在句子“You are happy”中，动词“are”是第二人称单数形式。

In the sentence "You are happy," the verb "are" is in ___the ___second ___person singular form.

这本语法书解释了动词如何根据第一、第二和第三人称进行变化。

This grammar book explains how verbs change for first, ___second, and third person.