Good　Calculation 　　 http://www.51education.net来自无忧英语教育幽默英语

"I am sorry, madam, but I shall have to charge you twenty dollars for pulling your boy's tooth." 　

　"Twenty dollars! Why, I understood you to say that you charged on ly four dollars for such work!" 
"Yes." replied the dentist, "but this youngster yelled so terribly that he scared four other patients out of the office."

如此计算 
“对不起，夫人，为您的孩子拔牙，我们要收取20美元。” 
　　“20美元！为什么？不是说只要4美元吗？”　　
“是的，”牙医回答说：“但是这孩子大喊大叫，把另外4个病人吓跑了。”