A.0;
B.1;
C.0.6;
D.1/6
[单选题]A.0;B.1;C.0.6;D.1/6
[单选题]A.B.C.D.
[单选题]A.0B.C.D.
[单选题]A.绝对收敛B.条件收敛C.发散D.收敛性与a有关