PDF is probably one of more important document formats. KPDF is a KDE program that can view and print them.
Start KPDF by pressing Alt-F2 and entering kpdf. Load a PDF file with + . KPDF displays it in its main window. On the left side, there is a sidebar with thumbnails and a contents view. Thumbnails give an overview of the page. The contents view contains bookmarks to navigate in your document. Sometimes it is empty, meaning bookmarks are not supported by this PDF.
To view two pages in the main window, select+ . The view depends on what last two options you activate in the menu.
Another nice option is to select the area in which you are interested with the select tool from the toolbar. Draw a rectangle and choose from the pop-up menu whether you need the selected area as text or as a graphic. It is copied to the clipboard. You can even save the area to a file.