题目

My running shoes areold，I need to buy new. A . very, one B . much，ones C . too，ones 答案：C将图中的变阻器接入电路中，当滑片向左移动时，要使电阻减小。下列哪种接法正确     A．a和b                       B．a和c                       C．c和d                      D．b和d