一个5阶矩阵A的列向量组线性无关,则A的秩为 ____

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.

A. Eight hours.
B. Two days.
C. One week.
D. Two weeks.

A. She preferred travelling.
B. She found it harder.
C. She didn't notice the difference.
D. She found it easier.

A. Because she wanted to visit Bangladesh.
Because she knew it would be hard.
C. Because there wasn't any other choice.
D. Because as a child she wanted to be a doctor.