The ZK framework has a rich set of components, a mark-up language, powerful development tools, and great documentation.

ZK框架具有一组功能丰富的组件、标记语言、功能强大的开发工具以及大量文档。

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The ZK framework has a rich set of components, a mark-up language, powerful development tools, and great documentation, along with being open source and an event-driven Ajax framework.

ZK框架拥有丰富的组件、一种标记语言、强大的开发工具和详细的文档，而且它是一个以事件驱动的开源ajax框架。

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As the name suggests, the former lets you mark up PDFs with text, arrows, shapes and highlighter tools, while the latter collates all the added notes into a single "summary" so users can get a visual overview of what's changed.

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