You can use three page layouts when viewing PDF documents. Single Page layout displays one page in the document pane at a time.
Continuous layout arranges the pages in a continuous vertical column.
Continuous - Facing layout arranges the pages side by side. If a document has more than two pages, the first page is displayed on the right to ensure proper display of two-page spreads. Choose Single Page, Continuous, or Continuous - Facing from the View menu.