请问不满秩是什么意思啊？提示如下:
NOTE: Model is not full rank. Least-squares solutions for the parameters are not unique. Some
      statistics will be misleading. A reported DF of 0 or B means that the estimate is biased.
NOTE: The following parameters have been set to 0, since the variables are a linear combination of
      other variables as shown.

                                    lasset =  0.67803 * Intercept

样本141个，7个自变量，19个行业控制变量，这有什么问题吗