翻译一下这段：
Section3.9 discusses the space/time tradeoff in which space requirements can
be reduced if you are willing to sacrifice time. However,the disk-based space/time
tradeoff principle stated that the smaller you can make your disk storage require-
ments, the faster your program will run. This is because the time to read informa-
tion from disk is enormous compared to computation time, so almost any amount
of additional computation to unpack the data is going to be less than the disk read
time saved by reducing the storage requirements. This is precisely what happens
when files are compressed.
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尝试着翻译第一句：
3.9节讨论了空间、时间的平衡，如果你愿意牺牲时间，那么空间的需求将减少。
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下面的：
然而基于磁盘的空间、时间的平衡原则规定：磁盘存储需求越小，你的程序运行的越快！
这是因为同计算时间相比从磁盘读取信息的时间是巨大的。
因此几乎任何数量的分析数据的额外计算将少于 通过减少存储需求所节省的磁盘读取时间。
这恰好是文件压缩所发生的情况。
个人翻译，仅供参考！