题目

Any dog’s love and devotion can feel like a miracle(奇迹). In a sense, Mason, a one-year-old dog, may be the most amazing one on the earth. The long-legged dog in North Smithfield, Alabama, was caught in a storm in his family’s garage last spring. His family thought he would be safe there, but the storm broke the garage door and Mason disappeared. Dozens of people died that day. Mason’s family were grateful just to be alive. But they were heartbroken at the thought that their sweet, playful companion had died. They combed the neighborhood, but Mason didn’t turn up. Three weeks a小明设计并连接了如图1所示测量电阻的电路，所使用的电源为两节干电池．该实验的原理是（用公式表示）________．请指出他在电路设计或连接上存在的一个问题：________；经改正后，所测得的数据绘出的图象如图2所示，该待测电阻的阻值为________Ω．