Let me try to explain, sorry if its confusing just ask me some more and I'll help. Yet kind of implies, something is to begin but it hasn't. "Did you eat?" "I didn't eat yet" <- is like I intend on eating but I did not start. "Are you sleep?" "not yet" <- i didn't even begin sleeping "Still" implies something was to end/or begin but hasn't for some reason. It is very similar to "yet" but i think it has negative connotations to it. To make it simpler for right now, think of "still" as like a kinda negative "yet" "Did you eat?" "I still didn't eat =/" <- I want to eat, but for some reason I am not able "Are you sleep?" " I still can't sleep" = <- I want to sleep but i am not able

"Yet" means up to a particular time. For example: The students had not yet written their exams. "Still" means that what was in the past has continued to exist. For example: I still believe my failure was a mistake. Note: "Yet" and "Still" have other meanings but you could begin from this introduction...