A.对
B.错
[判断题]A.对B.错
[单选题]=( )。A.B.C.D.
[单选题]A.B.πC.2πln2D.πln2
[单选题]A.B.x=2tC.D.
[单选题]A.5B.10C.15D.20
[问答题]------------.