First I want to thank everyone who responded to my post about conlang fluency. It's a big frustration I've been having and I'm trying hard to get past it. Now, my next question. I was thinking about definite articles and I wondered if I could actually replace "the" with the equivalent of "this" and "that" and so on. So essentially instead of saying "the cat" you would have to say "this cat" or "that cat". Is this something real languages do? Is there anything I would need to be careful of or watch out for if I went this route? Thanks for everyone's help.