I have no idea. I certainly can't. The trick is to keep reading and trying to learn stuff, but concentrate on the important stuff like concepts. Trying to memorise syntax is a waste of time. That is what the manuals are for. Almost everything on my website is there for my convenience so I have a copy/paste starting point. I could not complete many tasks from memory without referring back to my website of the manuals. I don't have time to memorise all contents of my website, let alone the manuals. The important thing to remember is what is possible and what is not. Knowing a feature is available and why it should be used is probably more important than remember the syntax.
For example, if someone says to me, "My backups take ages. How can I improve the speeed?", I think, "Perhaps incrementally updated backups and block change tracking will help?" I could not remember the syntax of these off the top of my head, even though I currently use them for all my backups. Fortunately, I can you use manuals, or even easier, use the stuff I wrote on it.http://www.oracle-base.com/articles/10g ... ed_backupshttp://www.oracle-base.com/articles/10g ... al_backups
See, the concept and the reason for using the feature is more important than knowing specifics about it...
Of course, the more you use something, the better you get a remembering it.