阅读短文，选择合适的答案。

    I'm a student in Class Four, Grade Three. My name is Mary. I'm nine. My twin brother's name is Li Mao. And we are in the same school, and in the same grade, but he is in Class Three. We are good students. I have a good friend. I call her Miss Ying Ying. Do you think Ying Ying is a good girl? No, you're wrong. She isn't a girl, but a cat. She is two years old, but she looks the same as her mother.