1. （解答题） 设
$$
A=\left(\begin{array}{ccc}
-2 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 3
\end{array}\right), B=\left(\begin{array}{ccc}
1 & 0 & 1 \\
0 & -2 & -1 \\
0 & 0 & 3
\end{array}\right), C=\left(\begin{array}{ccc}
1 & 0 & 0 \\
0 & -1 & 2 \\
0 & 2 & 2
\end{array}\right) \text {, }
$$
问 $A, B, C$ 哪些相似？哪些合同？
$$
A=\left(\begin{array}{ccc}
-2 & 0 & 0 \\
0 & 1 & 0 \\
0 & 0 & 3
\end{array}\right), B=\left(\begin{array}{ccc}
1 & 0 & 1 \\
0 & -2 & -1 \\
0 & 0 & 3
\end{array}\right), C=\left(\begin{array}{ccc}
1 & 0 & 0 \\
0 & -1 & 2 \\
0 & 2 & 2
\end{array}\right) \text {, }
$$
问 $A, B, C$ 哪些相似？哪些合同？