肯定句，这支笔是你的。否定句，这支笔你不是你的。疑问句，这支笔是你的吗？问你答句，就支笔是谁的？是我的！
你笨啊
i can swim
You are tall.You are not tall.Are you tall?Are you tall? Yes i am.
He is Tony. He isn't Tony. Is he Tony? Who is Tony?He is.
