下列关于极大无关组说法不正确的是( )
A. 一个向量组的秩等于其极大线性无关组里向量的个数
B. 一个向量组的极大无关组只有一个
C. 一个向量组与其极大线性无关组等价
D. 一个向量组的秩与其极大线性无关组的秩相等
一个5阶矩阵A的列向量组线性无关,则A的秩为 ____
What was Lisa's main task as a volunteer?
A. To clean the toliets in a hospital.
B. To teach in a local school.
C. To build toilets and help in an eye hospital.
D. To work as a cleaner in a school.
How long did the experience in the eye hospital last?
A. Eight hours.
B. Two days.
C. One week.
D. Two weeks.
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