A.
B.
C.
D.
[单选题]A.B.C.D.
[单选题]A.15B.16C.14D.18
[单选题]A.4+4πB.4+8πC.8+8πD.16+8π
[单选题]A.线环向右平移B.线环向上平移C.线环向左平移D.磁场强度减弱
[判断题]A.对B.错