Originally Posted by
The Summoner of Leviathan ^ I thought to express knowledge that you have, you are supposed to use the "ている" form of 知る: in this case it would express a resultant state. 知る on its own such as in "shirimasu" means more "come to know"/"get information about something" than "to know", or at least that is how my sensei explained it to the class. So to express something we know she told us to use "知っている" (知っています) and "知らない" (知りません) as the negative.
I was wondering that! Thanks! =O