如图所示电路,闭合开关S后,发现灯L1不亮,L2正常发光。此电路的故障可能是()
A:开关S接触不良
B:电灯L1灯丝断了
C:电灯L1短路
D:电灯L2短路
建国以来党的历史上具有深远意义的伟大转折是:
My Travel Plan
⒈On Saturday I will get ready for the trip.
⒉On Monday I will go to Beijing.
⒊On Tuesday I will go to the Palace Museum.
⒋On Wednesday I will go to Beihai Park.
⒌On Thursday I will go to Wangfujing Street.
⒍On Friday I will go home.
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下图中的生产工具发明于 ( )