I don’t know the girl in red. Could you tell me ________?

A．what is her name

B．how old is she

C．who is she

D．where she comes from

交流电路中功率因数不为1的原因是（）。

A．电路中存在着耗能元件R

B．电流是正弦交变的

C．电路中存在着相位的问题

D．电路中存在着L、C储能元件