Hello, I went to an Apple Store and asked two guys. They could not answer these questions satisfactory: 1. I want to open the same pdf file side by side. How can I do that without duplicating the file and changing the file name? One use is that in long pdf version of textbook, latter parts often refer to equations several pages before. I don't want to scroll back and forth. It would be idea to have the document displaced side by side so that I can have the equations in former pages on one side and the contents of latter part (the one I am reading on the other side) 2. After this is achieved, if I annotate one side of a document, the document on the other side (supposed to be the same document) automatically get updated. 3. Unlike Question 2, I annotate on one side but the document on the other side do not get updated. In this case, do I have to duplicate the original file first? Thanks.