题目

两长直导线平行放置，导线内通以等大同向电流，则当矩形线框abcd在两导线所在平面内从靠近右侧导线处向左侧导线平移靠近时如图2-1-6所示，线框中感应电流的方向应是(    ) 图2-1-6A.沿abcda不变                           B.沿adcba不变 C.由abcda变成adcba                 D.由adcba变成abcdaIn the lecture, the professor told his students how to write an ______ of a graduate paper, expressing the main argument.A. account B. abstract C. application D. address