[问答题]
[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.43B.34C.12D.14
[单选题]A.条件(1)充分,但条件(2)不充分B.条件(2)充分,但条件(1)不充分C.条件(1)和(2)单独都不充分,但条件(1)和条件(2)联合起来充分D