But because changes aren't reflected across content delivery networks immediately, ghost copies of files tend to linger for days or weeks.

但是，由于用户作出的更改不会立即反馈到内容分发网络上，文件的副本通常会以映像的形式存在数天或数周。

The problem relates to the way data is stored on large websites: While your personal computer only keeps one copy of a file, large-scale services like Facebook rely on what are called " content delivery networks " to manage data and distribution.

你的个人电脑里只保留了文件的一个副本，像脸谱网这样的大型服务器会通过内容分发网络来对数据进行管理和分配。