题目

I have a blind friend who lives in New York City.  41  we have never met face to face, we still  42  each other frequently. She is a  43  lady and has become like a sister to me. Her   44  and enthusiastic letters always   45  my spirits and the inspiring poems she shares with the world always bring a  46  to my face. She is all the more  47  due to the fact that she lost her  48  halfway through her life. She had to  49  her career and relearn to do everything that most of us take for granted. Many would have given up after such a  50  but not her.  51  , she 为了比较标有“2.5V”和“3.8V”小灯泡的额定功率大小，小明利用实验室器材进行了如下实验： (1)先连接电路，如图所示，测标有“2.5V”小灯泡的电功率，并记录结果如表一．然后小明从电路中取下“2.5V”小灯泡，换上“3.8V”小灯泡，并改用电压表“0～15V”量程进行实验．闭合开关后，调节滑动变阻器，他发现电压表示数始终无法达到3.8V．其原因是：______________． (2)补充实验条件后，小明继续实验并记录结果如表二．比较表一和表二数据，可知正常发光时，哪只灯泡的电功率大？____________________．