设矩阵 $\mathbf{A} = \begin{pmatrix} 1 & 0 & 1 \\ 1 & 1 & 2 \\ 0 & 1 & 1 \end{pmatrix}$ , $\pmb{\alpha}_{1}, \pmb{\alpha}_{2}, \pmb{\alpha}_{3}$ 为线性无关的 3 维列向量组, 则向量组 $A\pmb{\alpha}_{1}, A\pmb{\alpha}_{2}, A\pmb{\alpha}_{3}$ 的秩为