Because I'm really bad at using the space key, I noticed that cannot didn't get the red line underneath it. Curious as I am, I went and looked up the difference between cannot and can not, and I think I figured it out. "Cannot" means that you really can't do it, it is impossible, while "can not" would imply that you could if you wanted to, but you don't. Like "I cannot build a space ship" vs. "I can not give the dog a bath". I'm not sure btw, I got really confused by all the suggestions and arguments about it on the sites I checked. My issue with cannot, however, is that some people are taught that it is the preferred usage, yet I can't remember ever reading that word anywhere. Not even in older literature, and I've been looking out for it for a while now. Do people use cannot these days? And have I understood the difference correctly?