Most of the questions people ask me are easy. Can you use "nauseous" as a synonym of "nauseated" to mean "sick feeling"? The answer is right in the dictionary under the listing for "nauseous," and that answer is yes.
Is it true you're not supposed to end a sentence with a preposition? No, that's a myth, as any grammar reference from Fowler's to Strunk and White will quickly prove. Can you use "their" to refer to a singular person even though it's supposed to be plural? Again, the answer is right in the dictionary. Yes, according to the entry for that word, you can.
But recently I had to field some questions that aren't so easy. They came via a Twitter chat hosted by Copyediting.com and attended mostly by working copy editors. A lot of their questions eschewed the easy "can you?" business to focus on a tougher question: "Should you?"