be 动词：am / is / are

be 动词 是英语里最特别的动词——它有三张脸：am / is / are。

搭配口诀：

• I 用 am → I am a student.（我是学生）
• he / she / it 用 is → She is happy.（她很开心）
• you / we / they 用 are → You are my friend.（你是我的朋友）

缩写形式（口语里常用）：

• I am → I'm
• you are → you're
• he is → he's
• is not → isn't
• are not → aren't

疑问句：把 be 动词移到句首 → Are you ready?（你准备好了吗？）

否定句：be 动词后面加 not → I am not late.（我没迟到）

练一练：____ they at home? Yes, they ____. （答案：Are / are）