微机的外存储器指的就是软磁盘,而其它设备均不可作为外存储器。
参考答案:错
— ____________________?
— They are teddy bears.[ ]
A. What is it
B. What are these
设A为3阶矩阵,已知I+A,3I-A,I-3A均不可逆,则A一定相似于矩阵( ).