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 .”
“对不起,夫人,为您孩子拔牙我要收取20美元.”
“20美元!为什么?不是说好只要4美元.”
“是的,但是你的孩子大喊大叫,把另外四个病人吓跑了.”