题目

       Four days after Dad’s 67th birthday, he had a heart attack. Luckily, he survived. But something inside him had died. His enthusiasm for life was gone. He refused to follow doctor’s orders, and his sour attitude made everyone upset when they visit him. Dad was left alone.        So I asked Dad to come to live with me on my small farm, hoping the fresh air would help him adjust. Within a week after he moved in, I regretted the invitation. He criticized everything I did. I became frustrated. Something had to be done.        One day I read an article which said某电路如图所示，电源电压不变，R1＞R2。闭合开关S，将滑动变阻器的滑片P从a端滑到b端，则 A．电路中的总电阻变大B．R1两端电压不变C．R2的电功率变大D．R1电流的变化量小于R2电流的变化量