设AB为n阶方阵,且秩相等,既r(A)=r(B),则( ) A、r(A-B)=0B、r(A+B)=2 r(A) C、r(A,B)=2 r(A)D、r(A,B)<= r(A) + r(B) 发布时间:2025-12-20 06:03:06