已知矩阵 $\boldsymbol{A}=\left(\begin{array}{ccc}0 & -1 & 1 \\ 2 & -3 & 0 \\ 0 & 0 & 0\end{array}\right)$.
(I) 求 $\boldsymbol{A}^{99}$.
(II) 设 3 阶矩阵 $\boldsymbol{B}=\left(\boldsymbol{\alpha}_{\mathbf{1}}, \boldsymbol{\alpha}_2, \boldsymbol{\alpha}_3\right)$ 满足 $\boldsymbol{B}^2=\boldsymbol{B} \boldsymbol{A}$. 记 $\boldsymbol{B}^{100}=\left(\boldsymbol{\beta}_1, \boldsymbol{\beta}_2, \boldsymbol{\beta}_3\right)$, 将 $\boldsymbol{\beta}_{\mathbf{1}}, \boldsymbol{\beta}_2, \boldsymbol{\beta}_3$分别表示为 $\alpha_1, \alpha_2, \alpha_3$ 的线性组合.