A:甲
B:乙
C:丙
D:无法判断
The company always________great importance to the quality of their products. That's why there is always steady increase in sales year by year.
微波炉的炉门开关S1断开,控制开关S2闭合时,微波炉不工作,S1与S2都闭合时,微波炉正常工作,图中符合要求的电路是( )