“I'm sorry ，Madam ，but I shall have to charge you twenty dollars for pulling your boy's tooth .”
“Twenty d ollars! Why ，I understand you to say that you charged only four dollars for such work!”
“Yes，but this youngster yelled so terribly that he scared four other patients out of the office .”
“對不起，夫人，為您孩子拔牙我要收取20美元。”
“20美元！為什么？不是說好只要4美元。”
“是的，但是你的孩子大喊大叫，把另外四個病人嚇跑了。”