被称为“人体生命活动原动力”的气是(    )
   A．宗气    B．营气    C．元气    D．卫气    E．脾气

设X服从正态分布，E(x)=-1，E(X2)=4，取样本X1，X2，…，Xn则均值～( ) A． B． C． D．

A.174.24.96:6088/Latex/latex.action?latex=XGJhcntYfQ%3D%3D'
B.C.174.24.96:6088/Latex/latex.action?latex=TlxsZWZ0KCAtXGZyYWN7MX17bn3vvIxcZnJhY3sxfXtufSBccmlnaHQp'
D.E.174.24.96:6088/Latex/latex.action?latex=TlxsZWZ0KCAtMe%2B8jFxmcmFjezN9e259IFxyaWdodCk%3D'
F.G.174.24.96:6088/Latex/latex.action?latex=TlxsZWZ0KCAtXGZyYWN7MX17bn3vvIw0IFxyaWdodCk%3D'
H.I.174.24.96:6088/Latex/latex.action?latex=TlxsZWZ0KCAtMe%2B8jFxmcmFjezR9ezR9XHJpZ2h0KQ%3D%3D'

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下列关于二次积分交换积分次序错误的是 ( )A．B．C．D．

A.B../images/onErrorImg.jpg'
C.D../images/onErrorImg.jpg'
E.F../images/onErrorImg.jpg'
G.H../images/onErrorImg.jpg'

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