变异指标中,( )是离差指标,强调各变量值与其平均数的差别,能反映各变量值与其平均值的离散程度。
A.全距
B.修正距
C.平均差
D.标准差
E.方差
参考答案:C,D,E
方程3x3-24=0的根是______.
She said she had got ________ of looking at nature through dirty curtains and dusty windows.[ ]
A.interested
B.tired
C.grateful
D.concerned