第5题: [单项选择]设矩阵B的列向量线性无关,且BA=C,则( ) A. 若矩阵C的列向量线性无关,则矩阵A的列向量线性相关 B. 若矩阵C的列向量线性无关,则矩阵A的行向量线性相关 C. 若矩阵A的列向量线性无关,则矩阵C的列向量线性相关 D. 若矩阵C的列向量线性无关,则矩阵A的列向量线性无关 参考答案:D 答案解析:[详解] 设B为m×n矩阵,A为n×s矩阵,则C为m×s矩阵,且r(B)=n. 因为BA=C,所以r(C)≤r(A),r(C)≤r(B). 若r(C)=s,则r(A)≥s,又r
第20题: [单项选择]What does the passage tell us A. Confidence is more important than modesty. B. How to accept compliments given by westerners. C. The Chinese people are modest while westerners are confident. D. About the western culture. 参考答案:C