Soil fertility is soil productivity, which refers to the ability of soil to produce plant products.
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Soil is an important environmental factor, which is the buffer zone and filter of environmental pollutants.
为了避免陷入虚拟变量陷阱,如果一个定性变量有m类,则要引入m个虚拟变量。( )
判定系数R2的大小不受回归模型中所包含的解释变量个数的影响。( )