题目

____________ Li Bai, a great Chinese poet, was born is known to the public, but some won't accept it. A . That B . Where C . What D . Which 答案：B如图所示，当开关S闭合时，电压表，电流表均无示数，灯泡L1和L2都不亮，其故障原因可能是（ ）A．灯L1短路B．灯L1开路C．灯L2开路D．灯L2短路