There are some words we use almost exclusively in negative or interrogative clauses, most of which have corresponding words used almost exclusively for positive clauses. There’s just a handful of these, but they’re pretty common.
Sometimes we use the Present Simple tense or the Present Progressive tense for future meaning. For native English speakers, this seems normal. But when learning this (or teaching it for the first time, for that matter), it seems a bit odd. Why would we do this?