如图，两个滑动变阻器并联在电路中，滑动端均位于滑动变阻器的正中间，闭合开关后，两电流表示数相等，现移动滑动端，使两滑动变阻器的电阻改变量相同．若一个滑动变阻器的功率改变量是另一个滑动变阻器的功率改变量的两倍，则（　　）

A．滑动端移动方向相反，滑动变阻器的电阻改变量是其总电阻的三分之一　

B．滑动端移动方向相反，滑动变阻器的电阻改变量是其总电阻的六分之一　

C．滑动端移动方向相同，滑动变阻器的电阻改变量是其总电阻的三分之一

D．滑动端移动方向相同，滑动变阻器的电阻改变量是其总电阻的六分之一

短文填词（共10小题，每小题1分，满分10分）

阅读下面的短文，用三种形式完成短文，使文章语义完整，连贯。（①根据上下文填空；②用所给单词的正确形式填空；③根据单词所给首字母填空。每空一词。）请将答案写在右边对应题号的横线上。

Dear Christie，

I’m here in the National Park, in     （southeast）California.                           72.    

I have been t    around the state of California for three weeks                                   73.    

now, It's very different from        I have seen in American movies.                         74.    

Not everyone is rich and not everyone l     near the beach. I first                             75.    

travelled southeast      rich farmland then to the central part.                                    76.    

They grow e     here including cotton，vegetables，nuts and                                   77.    

fruit．They raise cattle too．Then I traveled   （far）southeast into                          78.    

mountains and desert. Californians are very friendly,      they are                              79.    

from many different r    and cultures. Every cuIture has its own                              80.      ，

music，food and art. I show great interest in them．                                                   81.    

Wish you were here. Give my love to Paula.

Yours，

           George