A摩尔曼斯克____          ①巴西

B神户____                ②澳大利亚

C孟买____                ③印度

D悉尼____                ④俄罗斯

E里约热内卢____          ⑤日本

填上合适的数．

$2\frac{2}{5}$ = $\frac{\left(\right)}{5}$ = $\underset{\_}{}÷\underset{\_}{}$

①该实验的目的是：____．

②为进行多次实验，三位同学各自设计了三个不同的实验方案，简述如下表所示．

（a）上述三个方案中，能实现“多次实验，减小误差”的方案有____（填序号）；方案Ⅲ与另两个方案相比，优点有：____（写出两点即可）．

（b）小明同学根据方案Ⅲ，准备测量阻值约为20欧的电阻，实验所提供的器材齐全完好，其中：电源电压为6伏且保持不变，电流表、电压表规格如图所示，滑动变阻器有两种规格（分别标有“5欧 3安”和“50欧 1.5安”字样）．

小明对所提供两种规格的滑动变阻器，提出了问题：实验中，两种变阻器是可以随意用一个变阻器，还是其中一个更适合实验？请你根据实验的相关条件，帮助小明解决问题并简要说明理由．____

 Liu Wei is very famous in China because he can play the piano with his toes(脚趾).

 One day when Liu Wei was only 10 years old, he played a game with some friends. He lost both his arms because of electricity.

 Liu Wei was very sad when both his arms were cut off after the accident. But soon he had to make a choice.

“For people like me, there were only two choices. One was to give up all the dreams, which would cause a quick death. The other was to work hard without arms to live an excellent life.”says Liu Wei.

 Liu Wei’s dream was to be a pianist. He learned to play the piano with his toes. And teaching himself to play the piano with his toes was very hard. Many times he wanted to give up, but his parents went on encouraging him and he wanted to make his parents proud.

 Maybe you can not believe that Liu Wei is able to play well only with his toes. The audience(观众) were deeply moved and very excited when they watched his performance.