题目设A、B为n阶方阵,A非零,且AB=0,则必有A. BA=0B. |B|=0C. B=0D. (A+B)^2=A^2+B^2设A、B为n阶方阵,A非零,且AB=0,则必有A. BA=0B. $|B|=0$C. B=0D. $(A+B)^2=A^2+B^2$题目解答答案B. $|B|=0$