When we want to ask someone to do something or make an imperative action, and we don’t know that person well and/or they are older than us, then we need to use the honorific particle (으)시.
V + 세요
1. When we are speaking in present tense, using the present verb conjugations (아/어/여) then we just replace the verb stem ‘다’ with 으세요 if the verb ends in a consonant or 세요 if the verb ends in a vowel.
V + (으)시 + …
2. Otherwise if the verb has another ending attached to it at the end, then we add (으)시 before the ending.
3. Because this is a polite particle, we have to use ‘요’ at the end or (ㅂ/습)니다 which are polite or honorific endings. We cannot use this with a casual or plain ending. We will discuss more about these endings soon.
푹 쉬세요. = Get a good rest.
빨리 오세요! = Come fast!
괜찮으시죠? = It’s ok right?
무엇을 하셨어요? = What did you do?