A.
B.
C.1/2
D.-1/2
[单选题]A.B.C.1/2D.-1/2
[单选题]A.B.C.1/2D.-1/2
[单选题]A.B.C.1/2D.-1/2
[单选题]A.B.C.1/2D.-1/2
[单选题]( ).A.对任意闭曲线L,I=0B.在L为不含原点在内的闭区域的边界线时I=0C.D.在L含原点在内时I=0,不含原点时I≠0
[单选题]( ).A.B.C.D.
[单选题]( ).A.对任意闭曲线L,I=0B.在L为不含原点在内的闭区域的边界线时I=0C.D.在L含原点在内时I=0,不含原点时I≠0
[单选题]( ).A.B.C.D.
[单选题]( ).A.对任意闭曲线L,I=0B.在L为不含原点在内的闭区域的边界线时I=0C.D.在L含原点在内时I=0,不含原点时I≠0
[单选题]( ).A.B.C.D.