题目

While I studied at school, I felt a great difficulty in learning my Latin translations.I was always very  1   in using a dictionary, and  2   in most difficult, while so other boys it seemed no  3   . I formed an alliance(盟友) with a boy in the Sixth Grade. He was very clever and   4    read Latin as easily as English. My friend for his part was almost as  5   trouble by the English essays he had to write for the headmaster as I was   6  these Latin words. We agreed together that he would  7  me my Latin translations and that I should do his **ays. The arrangement  8�在“测定电源电动势和内阻”的实验中，实验室仅提供下列实验器材：A．两节旧干电池，每节电动势约1.5VB．直流电压表Vl、V2，量程均为0～3V，内阻约3C．电流表，量程0～0.6A，内阻小于1D．定值电阻R0，阻值2E．滑动变阻器R，最大阻值15F．导线和开关若干（1）请根据连接的实物图甲，在图乙虚线框中画出对应的电路图；（2）根据图甲电路进行实验，测得多组U、I数据，作出U-I图象，求出电动势和内阻的值均小于真实值，其产生误差的原因是 。（3）实验过程中，由于电流表发生了故障，某同学又设计了图丙所示的电路测定电源的电动势和内阻，实验中移动滑动变阻器触头，记录Vl和V2的值如下表所示，用测出的数据在图丁中绘出U1－U2图线。组数123456电压U1/V0.801.251.531.721.871.98电压U2/V1.601.872.042.152.242.31（4）由图线可得被测电池组的电动势E= V，内阻r= Ω．（结果保留两位有效数字）