阅读材料，然后从各小题所给的四个选项中选出最佳选项。When you run into someone, will you say "Sorry"? When you get help from others, will you say "Thanks"? You will if you are polite.
A new study shows students seem to be less and less polite as they grow up and middle school students aren't as polite as primary school students. They start to swear（说脏话） and laugh at their classmates.
Wu Lin, 13, of Fujian, said, "More than 10 of 22 boys in my class often swear. We just swear for fun most of the time. But later, I understood that it was bad for me. So I stopped."
Li Fangfang, 13, Beijing, knows that laughing at others can really hurt. "Once, a classmate put up her hand to answer a question. But she didn't give the right answer. Then some classmates laughed at her," Li said. "From that day on, she never put up her hand. Those laughing kids hurt her a lot."
"Impoliteness comes from students' growing pains（痛苦）," said Wang Yamin, a teacher of a university. "Some middle school students become impolite because their classmates or parents do things that way. They think it's cool and funny. But our people are famous for politeness. Every student should speak and do things politely to respect （尊敬） others and let others respect you."
