操作系统的安全措施可以从隔离方面考虑。以下哪一个不是隔离的措施
A．物理隔离
B．逻辑隔离
C．时间隔离
D．空间隔离
参考答案：D
解析： 选项A物理隔离是使不同安全要求的进程使用不同的物理实体；选项B逻辑隔离是指限制程序的存储，使不能存取允许范围以外的实体；选项C时间隔离是使不同进程在不同的时间运行。以上三项都属于隔离措施，而选项D空间隔离是实现操作系统安全的另一种方法，不是隔离措施。
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| Across the street from our home was a school and I would often watch the kids as they played basketball during the break. I often noticed a small 1 playing with boys. I watched in 2 as she ran circles around the other kids. She 3 to shoot jump shots just over their heads and into the net. The boys always tried to stop her but no one could. At other times I saw her playing alone, sometimes until 4 . One day I asked her way she 5 so much. She looked 6 in my eyes and without a moment of hesitation she said, "The only way I can go to 7 is to get a scholarship. I believe that I would get it if I were good enough at 8 . My Daddy told me if the dream is big enough, the facts don't 9 ." Then with a determined smile she ran towards the court, I watched her 10 those junior high school years and into high school. Every week, she led her team to victory. One day in her senior year, I saw her sitting in the grass, head 11 in her arms. The coach told her that at 5 feet 5 inches she would 12 never get to play for a top ranked team--much less offered a scholarship-so she should 13 dreaming about college. I asked her if she had talked to her dad about it yet. She 14 her head from her hands and told me that her father said those coaches just did not understand the 15 of a dream. He told her that if she truly wanted a scholarship, 16 could stop her except one thing-her own attitude. The next year, 17 she and her team went to the Northern California Championship game, she was seen by a college coach. She was indeed 18 a scholarship, a full one. She was going to get the college education that she had 19 and worked toward for all those years. It's 20 : If the dream is big enough, the facts don't count. | ||||
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