The backup copy has the same name as the document, but the extension is .BAK. If the backup folder already contains such a file, it will be overwritten without warning.
备件副本与原文档具有相同的名称，但扩展名为 .BAK。如果用于保存备件副本的文件夹中已经含有这样一个文件，将覆盖该文件且不显示警告。