下列属于尿毒症面容的特征的是()
A．面色萎黄
B．颜面浮肿
C．皮肤苍白
D．皮肤发绀
E．皮肤干燥
参考答案：A, B, C, D, E
设X1，X2，…，Xn为来自总体X的简单随机样本，其中E(X)=μ，D(X)=σ2，令U=
，则ρUV=______．
You can go to Nancy. She is always .[ ]
A. ready to h elp others
B. ready to help the others
C. ready for help others
D .ready for help the others
，则ρUV=______．