If you already have a slide presentation that was created in Microsoft PowerPoint or AppleWorks, you can import it into Keynote and continue to work on it.
As much as possible, Keynote preserves the original document’s text, colors, layout, and other formatting options.
In Keynote, choose File > Open. In the Open dialog, find the document you want to import and click Open.
In the Finder, drag the PowerPoint or AppleWorks document icon to the Keynote application icon.