直流输电系统能保持稳定运行的条件是（）。
A.电流控制
B.电压控制
C.电流裕度法
D.功率控制
参考答案：C
Which of the following is NOT a method of terminating a forward contract prior to expiration ()
A. Exercise a swaption.
B. Make an agreed upon payment to the counterparty.
C. Enter into an offsetting forward contract with a party not involved in the original forward contract.
