Charles Lyell made a good estimate of the Tertiary Period from the fossil record, but his method could not be extended to earlier geological periods.

查尔斯·莱尔根据化石记录对第三纪作出了很好的估计，但他的方法不能扩展到更早的地质时期。

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It also provides a method to define a set of hard and soft disk block and file allocation limits and the grace periods before the soft limit becomes enforced as the hard limit.

它还提供了一种方法来定义一组磁盘块和文件分配的硬、软限制，以及软限制强制实施为硬限制前的过渡期。

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In different historical periods, the object of study and method of study vary.

在不同的历史时期，研究对象和研究方法有所不同。

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