设A,B为n阶矩阵,记r(X)为矩阵X的秩, (X Y)表示分块矩阵,则-|||-(A) (A AB)=r(A). (B) (A BA)=r(A).-|||-(C) (A B)=max r(A),r(B) . (D) (A B)=r((A)^T(B)^T).