求向量组 $\alpha_1=\left(\begin{array}{l}1 \\ 0 \\ 2 \\ 1\end{array}\right), \alpha_2=\left(\begin{array}{c}1 \\ -1 \\ 1 \\ 0\end{array}\right), \alpha_3=\left(\begin{array}{l}1 \\ 1 \\ 3 \\ 2\end{array}\right), \alpha_4=\left(\begin{array}{l}1 \\ 3 \\ 2 \\ 1\end{array}\right)$ 的秩及一个最大无关组。