题目

--- We have few vegetables for dinner. Could you go and buy                 ?      --- Yes, sure. But I don't have                  money.       A. any; any              B. some; any   C. any; some  D. some; some 答案：B    如图所示，条形磁铁由静止开始下落穿过闭合线圈，线圈中产生电流，关于这一过程下列说法中正确的是（       ）A．条形磁铁相当于一个电源B．穿过线圈的磁通量一直增加C．线圈对条形磁铁先做负功，后做正功D．条形磁铁的重力势能和动能之和在减少