根据短文内容，判断下列句子的正误。

    Polite people are nice to other people. Polite people never talk loudly in public(公共场合), in the library, in hospital, in the cinema... When they ask for something, they usually say, "Please". And they get something, they say, "Thank you". When they meet a person, they always say, "Hello" or "Nice to see you." When they leave, they usually say, "Goodbye". A polite student never comes to school late. If you are late, you should say, "I am sorry." to the teacher after class. In class if you can't answer the teacher's question, you can say, "I am sorry. I don't know."