A.
B.
C.
D.
[单选题]A.B.C.D.
[单选题]A.跳跃间断点B.可去间断点C.第二类间断点D.连续点
[单选题]A.126B.128C.252D.256
[单选题]A.30B.48C.57D.72
[单选题]A.串联电压负反馈B.串联电流负反馈C.并联电压负反馈D.并联电流负反馈