Select the View Mode to activate the View Mode submenu, as below:
Single Page View
Selecting the Single Page View (the default option) will view the PDF document on a page per page basis one full page at a time.
Below is an example of the Single Page View:
Single Page Continuous View
Selecting the Single Page Continuous View will show the PDF pages in flowing, continuous fashion, which will allow the viewing of part of two pages of the PDF at once.
Below is an example of the Single Page Continuous View:
Two Page View
Selecting the Two Page View option will show two PDF pages to be lined up next to each other horizontally, with a PDF page being able to be fully viewed at a time.
Below is an example of the Two Page View:
Two Page Continuous
Selecting the Two Page Continuous view option will allow two PDF pages to be lined up next to each other horizontally, with side scrolling being enabled to show part of each PDF page next to each other.
Below is an example of the Two Page Continuous View: