$$
(I)\left\{\begin{array}{cc}
a_{11} x_1+a_{12} x_2+\cdots+a_{12 n} x_{2 n} & =0 \\
a_{21} x_1+a_{22} x_2+\cdots+a_{22 n} x_{2 n} & =0 \\
& \vdots \\
a_{n 1} x_1+a_{n 2} x_2+\cdots+a_{n 2 n} x_{2 n} & =0
\end{array}\right.
$$


的一个基础解系为 $\left(b_{11}, b_{12}, \cdots, b_{12 n}\right)^{ T },\left(b_{21}, b_{22}, \cdots, b_{22 n}\right)^{ T }, \cdots,\left(b_{n 1}, b_{n 2}, \cdots\right.$ ， $\left.b_{n, 2 n}\right)^{ T }$ ，

试写出线性方程组
（ II ）$\left\{\begin{array}{lc}b_{11} y_1+b_{12} y_2+\cdots+b_{12 n} y_{2 n} & =0 \\ b_{21} y_1+b_{22} y_2+\cdots+b_{22 n} y_{2 n} & =0 \\ & \vdots \\ b_{n 1} y_1+b_{n 2} y_2+\cdots+b_{n 2 n} y_{2 n} & =0\end{array}\right.$
的通解，并说明理由．