I was having a hard time figuring out that the imperative usually involves changing the tu form to the 3rd person from present tense, but not always when the verb is irregular (and so many are). Sitesurf had been quite helpful previously, so this comment was a continuation from a discussion on another thread. This particular rule is tricky to learn in the Duolingo method, I think. I had to dust off my little red verb book, but now I get it- it's a weird rule with a lot of exceptions, essentially. sorry to confuse you!