动力源开关电源更换交流侧板件或器件前,不应当()。
A.准备好万用表等工具仪器
B.切断市电输入,启动油机为设备供电
C.确保电池后备时间正常
D.切断交流输入
参考答案:B
They are volunteers for the Olympic Games, and they everybody to obey the traffic regulations.
A.adapt to
B.attend to
C.apply to
D.appeal to
汇率超调