题目内容

某操作系统的磁盘文件空间共有500块，若用字长为32位的位示图管理磁盘空间，试问：(1)位示图需多少个字(2)第i字第j位对应的块号是多少(3)给出申请/归还一块的工作流程。

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The newborn can see the difference between various shapes and patterns from birth. He prefers patterns to dull or bright solid colors and looks longer at stripes and angles than at circular patterns. Within three weeks, however, his preference shifts dramatically to the human face.Why should a baby with so little visual experience attend more to a human face than to any other kind of pattern" Some scientists think this preference represents a built in advantage for the human species. The object of prime importance to the physically helpless infant is a human being. Babies seem to have a natural tendency to the human face as potentially rewarding. Researchers also point out that the newborn wisely relies more on pattern than on outline, size, or color. Pattern remains stable, while outline changes with point of view; size, with distance from an object; and brightness and color, with lighting.Mothers have always claimed that they could see their newborns looking at them as they held them, despite what they have been told. The experts who thought that perception (知觉) had to await physical development and the consequence of action were wrong for several reasons. Earlier research techniques were less sophisticated than they are today. Physical skills were once used to indicate perception of objects-skills like visual tracking and reaching for an object, both of which the newborn does poorly. Then, too, assumptions that the newborn"s eye and brain were too immature for anything as sophisticated as pattern recognition caused opposing data to be thrown away. Since perception of form was widely believed to follow perception of more "basic" qualities such as color and brightness, the possibility of its presence from birth was rejected. What does a newborn baby like to see most in the first two weeks