Я обычно использоваю "sure, of course, certainly" ответить на запросы: "May I have some water?" - "Sure / of course / certainly" или ответить на вопросы: "Are you coming with us?" - "Sure / of course / certainly" похожи на «конечно» на русском, можно сказать: "Of course I'm going" / "Certainly I'm going" но "sure / of course" - более дружны, а "certainly" - очень вежлив My Russian is still bad, but I hope this helps! :)

http://twominenglish.com/video/205-Sure_Certainly_Definitely_Absolutely_English_G.html The above link does a good job of addressing all of them except "of course", which is addressed below. :) https://www.italki.com/question/81907