Therefore, the amount of time required for any particular memory access is completely unknown (if the memory is swapped out, who knows how long it will take).

因而，某一内存访问所需的时间是完全未知的(如果内存被换出，所需时间的长短是不可知的)。

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We've also presented and explained how to use several powerful new features, such as revalidation in memory and access to type information — something developers have been asking for for a long time.

我们还展示并解释了如何使用几个强大的新特性，例如内存中的重新验证以及对类型信息的访问——这些都是开发人员长期以来梦寐以求的特性。

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The reason that this process takes so long is that a computer's operating system must be loaded from its hard disk into its random-access memory (RAM) every time the machine is turned on.

这个过程花这么长时间的原因是，每当打开计算机时，计算机的操作系统必须从硬盘载入到随机存取存储器(RAM)。

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