题目

Among rich countries, people in the United States work the longest hours. They work much longer than in Europe. This difference is quite surprising because productivity per hour worked is the same in the United States as it is in France, Spain and Germany, and it is growing at a similar speed. In most countries and at most times in history, as people have become richer they have chosen to work less. In other words, they have decided to “spend” a part of their extra income on a fuller personal life. Over the last fifty years Europeans have continued this pattern, and hours of work have fal 在“用电流表和电压表测定电池的电动势和内电阻”的实验中． ①备有如下器材： A．干电池1节； B．滑动变阻器(0～20 Ω)； C．滑动变阻器(0～1 kΩ)； D．电压表(0～3 V，内阻约2 kΩ)； E．电流表(0～0.6 A，内阻约2 Ω)； F．电流表(0～3 A)； G．开关、导线若干 其中滑动变阻器应选________，电流表选________．(只填器材前的序号) ②用实线代表导线把下图所示的实物连接成测量电路(图中有部分线路已连好)． ③某同学记录的实验数据如下表所示，试根据这些数据在图中画出U－I图线，根据图线，得到被测电池的电动势E＝________V，内电阻r＝________Ω．