根据SJ2112—82标准，辅助设备（输入）额定信号源阻抗的优选值为（）Ω平衡。
A、300
B、600
C、40k
D、260m
参考答案：B
1，1，6，21，81，306，()
A．1017
B．1161
C．1285
D．1527
Which of the following is TRUE about the call feature of a bond It:（）
A. stipulates whether and under what circumstances the bondholders can request an earlier repayment of the principal amount prior to maturity.
B. describes the credit risk of the bond.
C. stipulates whether and under what circumstances the issuer can redeem the bond prior to maturity.
