用 Laplace 定理计算
$$
D=\left|\begin{array}{cccccc}
0 & \cdots & 0 & a_{11} & \cdots & a_{1 n} \\
\vdots & & \vdots & \vdots & & \vdots \\
0 & \cdots & 0 & a_{n 1} & \cdots & a_{n n} \\
b_{11} & \cdots & b_{1 m} & c_{11} & \cdots & c_{1 n} \\
\vdots & & \vdots & \vdots & & \vdots \\
b_{m 1} & \cdots & b_{m m} & c_{m 1} & \cdots & c_{m n}
\end{array}\right|
$$