He is my brother.they are my sister 观察句子,为什么he后面用is而they后面用a

He is my brother.they are my sister 观察句子,为什么he后面用is而they后面用a my father has a brother .he is my u【 】 后面填什么好?急. he is my brother 变成复数句子 They are my parents,my sister,my brother and I. My brother likes action movies. He thinks they are exciting My parents are old.___ is my brother.He is a doctor.Kate is My aunt has a brother .he is not my uncle.who is he?he is my My brother is coming to see me.He will come here 为什么用in a fe 英语翻译They are my(boys).(Uncle Sam)My sister is a(hello girl). They are my grandpa,father,mother,brother and I.中为什么用I而不用me? They are girls(改为单数句子） She is my sister,(改为复数句子） 用 am is are have has 填空; My brother ( ) stundent.They ( ) an