A.对
B.错
[问答题]
[单选题]A.1倍B.5倍C.12倍D.18倍E.21倍
[单选题]( ).A.2πB.-2πC.0D.π
[判断题]( )A.对B.错
[单选题]=( )A.1B.C.D.
[单选题]A.B.C.D.