Suddenly raising the price 突然涨价

A man took his son to have an aching tooth pulled by the dentist. When it had been drawn, the man was asked to pay ten dollars for it.

"Ten dollars!" he exclaimed surprised and said to the dentist, "I know you only charge two dollars for pulling a tooth. Why do you raise the price at will（随意）?"

The dentist said, "Yes, but your son cried out so loud that four other patients were frightened away."

有个人带着他的儿子去找牙医给他拔掉一只痛牙。牙医把他的牙齿拔掉后，要这个人付10美元。

这个人惊讶得大叫道：“10美元！我知道你拔一只牙是只收2美元，为什么任意涨价呀？”

牙医说：“没错，可是你的儿子喊叫得那么凶，把另外四个病人都吓跑了嘛！”