题目

两根材料相同的均匀导线x和y，x长为L，y为2L，串联在电路中，沿长度方向电势变化如图所示，则x，y导线的横截面积之比为（                                              ）                                                                                                                                                  A． 2：3         B． 1：3  C． 1：2He always gets angry if he is kept _______ for five minutes.A. waiting B. wait C. to wait D. waitting