设λ1、λ2是矩阵A的两个不同的特征值，ζ、η是A的分别属于λ1、λ2的特征向量，则以下选项正确的是( )。
A．对任意的k1≠0和k2≠0，k1ζ+k2η都是A的特征向量
B．存在常数k1≠0和k2≠0，使得k1ζ+k2η是A的特征向量
C．对任意的k1≠0和k2≠0，k1ζ+k2η，都不是A的特征向量
D．仅当k1=k2=0时，k1ζ+k2η，是A的特征向量
参考答案：C
Lillian Hanson, a college student, expects to graduate in about two years. What makes Mrs Hanson different from her classmates is her age-----73 years. She has been studying at college, a few courses at a time, for 27 years. When Lillian Hanson graduated from high school, she went to the bank to borrow money for further education. The banker gave her no encouragement. He didn‘t think that a country girl should borrow money to go to college. He thought she should be at home doing work in the house or around the farm. So Lillian Hanson went home and raised a family of nine children instead of going to college. Mrs Hanson never forgot her dream of getting a higher education. When her children were grown, she tried again. She finds that it is the hardest part of going back to school at her age to sit in class for long periods of time. Because she is not as quick as she used to be, Mrs Hanson often gets up and walks around classes to keep from getting stiff(不灵活). At the beginning of a course in using the computer, the other students all stood up to give her a warm welcome when she introduced herself and explained why she was there and what her aims were. 小题1: Mrs Hanson couldn’t go to college immediately after she graduated from high school because _____.
a. she began her studies at college. b. She finished high school. c. She got married and gave birth of nine children. d. She had her 73 rd birthday. e. She went to the bank to borrow money.
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