Be动词

am 只和 I 搭配使用

I am a girl. I’m a boy.

is 和 He She It以及其他单数名词使用

He is Wang Ming. She is sad. It is a dog. It is cool. This is a ruler. That is a pencil. My name is Wang Zimo. Your name is Li Xin. My mum is very happy.

are 和 You, We, They以及其他复数名词使用

You are a baby. (你是一个宝宝） You are babies. (你们是宝宝） We are students. (我们是学生) They are Monkey. (它们是猴子） These stories are fun. (这些故事很有趣) Those books are new. (那些书是新的)