从某班的一次数学测试卷中任意抽出10份,其得分情况如下:81,98,43,75,60,55,78,84,90,70,则这

从某班的一次数学测试卷中任意抽出10份,其得分情况如下:81,98,43,75,60,55,78,84,90,70,则这次测验成绩的样本方差是( ).

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第31题应填入( )

第31题应填入( )A.off B.free C.on D.back

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Martin Henfield talks about some of his experience(经历) as a

Martin Henfield talks about some of his experience(经历) as a twin: when we were s

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() There was so much noise that the speaker couldn't make h

() There was so much noise that the speaker couldn't make himself__________. A.

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