1.The necessary and sufficient conditions of similarity of two idempotent matrices are proved, the idempotency of linear combinations of two idempotent matrices is discussed.

1.摘证明了数域上两个同阶幂似的充条件是有同的秩；给出了幂的似标准型；讨论了两个幂的线性组合仍是幂的充条件。