题目

In the days when an ice cream sundae cost much less, a 10-year-old boy entered a hotel coffee shop and sat at a table. A waitress put a glass of water in front of him. “How much is an ice cream sundae?” “Fifty cents,” replied the waitress. The little boy pulled his hand out of his pocket and studied a number of coins in it. “How much is a dish of plain ice cream?” he required. Some people were now waiting for a table and the waitress was a bit impatient. “Thirty-five cents,” she said rudely. The little boy again counted the coins. “I’ll have the plain ice cream,” he said.研究物理问题时经常用到科学的研究方法．如探究“真空能否传声”就是在实验基础上进行理想推理而得出结论，研究以下问题的方法与此方法相同的是（ ）A．分子热运动B．牛顿第一定律C．电阻上的电流与两端电压的关系D．磁场用磁感线来描述