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【单选题】
To test whether there is a difference between male and female indicators in a sampling study, in what situation should we use two-sided test? ( )A.
We don't know whether the average platelet level is higher in men or higher in women.
B.
it is known that women have lower average lung capacity than men
C.
it is known that women have lower levels of hemoglobin than men
D.
it is known that there is no difference in the number of white blood cells by gender
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【简答题】设 x 、y均为正实数，且 ，以点 为圆心, 为半径的圆的面积最小时圆的标准方程为 ▲ .
【简答题】装饰设计素描的秩序化构成包括 、 、 。
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