两种拆法：按范围提取几页成一个新 PDF，或把每一页拆成单独文件打包下载。全部在浏览器本地完成。Two ways to split: extract a page range into a new PDF, or split every page into its own file in a zip. All local, nothing uploaded.
加密（带打开密码）或损坏的 PDF 无法读取，请先解除密码。页码从 1 开始。Password-protected or damaged PDFs cannot be read; remove the password first. Page numbers start at 1.