In an American classroom, a teacher asked a Chinese girl to answer a question. She stood up and smiled, without making any sound. The American teacher looked at himself and didn't see anything funny. So he asked her the question again.The girl just smiled but said nothing. The teacher was angry. He didn't know that the girl smiled to cover her embarrassment because she didn't know how to answer the question. In a dining room in Beijing, an Englishman was careless and dropped a plate. The Chinese who saw this began to laugh. The Englishman felt uncomfortable and even got angry."They are laughing at me," he thought. In fact ,the Chinese laughed not at the Englishman or his bad luck---whether  he is a foreigner or a Chinese. The laughter has some feelings, don't take it so seriously ;laugh it off, it's nothing;such things can happen to any of us,etc. What does the writer want to tell us?
Chinese students are impolite. Smiles and laughter always bring happiness. American people are easy to get angry. Smiles and laughter don't mean the same thing to different people.