题目

I received a call today asking if I would be willing to bring food to a family in need. The mother was having a major operation and would be   41   down for several weeks. Of course, I responded with an   42   “Yes! ”. As I planned the   43   in my head, I   44   on how many times over the years I had been asked to prepare food. I have done so  45  times with a very open heart. But the truly   46   thing is   47   I have received double over the course of my life. When my mother passed   48  , our house was filled with fresh dinners for weeks. A woma某同学用如图所示的电路探究“电流与电阻”的关系，已知选用的电源电压恒为6V．请回答下列问题：①实验中，使用电阻箱代替定值电阻的好处是便于改变电阻的阻值便于改变电阻的阻值．②该同学在探究的过程中，将观察到的实验数据及时记录到了下面的表格里．分析表中数据，不能不能（选填“能”、“不能”）得到电流与电阻成反比的关系，造成这种结果的原因是：未保持电阻来的电压不变未保持电阻来的电压不变．你认为，表格中的每组电压、电流、电阻的数据与欧姆定律相符相符（选填“相符”、“不符”）． 实验序号 R1/Ω I/A U/V 1 5 0.4 2 2 10 0.3 3 3 15 0.24 4 20 0.2 4③根据该同学的实验思路，可推知表格中第三次实验的电压值应为3.63.6V④如果用此电路进行正确的探究，并以第一次的实验数据为标准，则在进行第二次实验时，他应将滑片向右右（选填“左”、“右”）移；要顺利完成表格中的4组数据的测量，变阻器R2的最大阻值不得小于4040Ω．