以下()情况导致直流50/100Hz保护动作。
A.交流单相故障
B.启停直流
C.阀触发系统异常
D.功率提升
参考答案:A, C
Thank you for your great dinner. I really enjoyed it.()you enjoyed it.
A.I'm so glad
B.I'm sorry
C.What a pity
D.Surprisingly