They are all related to 그렇다 and its applications as shown below. - 그렇다 (= 그러하다) (a) = "is like that; is so/such" - indicates something has certain quality. - 그렇게 (adv) = "so; that much; to that extent" - 그렇다 + -게 (suffix to make an adverb from an adjective). - 그렇게 하다 (v) = "do so; do that; do (something) in that way". - 그리하다 (v) = contraction of 그렇게 하다. - 그러다 (v) = another contracted form of 그렇게 하다. 그렇다 can conjugate like these at sentenc ending for the present tense. 1. 그렇습니다 (formal, polite). 그렇습니까? (question form - Is that so?) 2. 그렇다 (plain, impersonal). 그러냐? 3. 그래요 (polite; 그러해요 -> 그래요). 그래요? (same for statement and question) 4. 그래 (plain, familiar; 그러해 -> 그래). 그래? (same) 그렇게 하다 may be used as is, or shortened to 그러다 or 그리하다. 그러다 conjugations: 그러합니다/그러합니까?, 그런다/그러냐?, 그래요/그래요?, 그래/그래? 그리하다 conjugations: 그리합니다/그리합니까? 그리한다/그리하냐?, 그리해요/그리해요?, 그리해/그리해?. Note that both 그렇다(a) and 그러다(v) conjugate to 그래(요) in the informal register. So 그래요 can mean "It is so; That's right" (a) or "Go ahead and do that/so)" (v). Additionally, it can also represent 그렇다고 해요 (They say it is so), an indirect reported speech. e.g. - Q: 날씨가 너무 춥죠? (It's too cold, isn't it?) A: 그래요 (Yes, it is) - adjectiv usage. - A: 과장님, 먼저 퇴근하겠습니다. (Chief, I'll take off now.) B: 그래요 (Okay, go ahead) - used as a verb. - 옆집 청년이 롤림픽에 나간대요. (They say the youngster next door is going to the Olympics). - 그래요? (Is that right? = Do they say that? - reported speech). 그렇습니까? is just a formal version of 그래요? (oftne used when addressing an audience). 그렇군요 is 그렇다 with -군(요) ending. -군요 expresses a mild surprise, as if noticing something for the first time. So it is different from the others above as they have no special connotation other than formality and politeness. e.g. 아, 출근 하시는군요! (Why, I see you are off to work!) Finally, similar sets of words exist for 이렇다 and 저렇다, like 이래요, 저래요, etc.

그래요 - Alright 그렇군요 - I see 그렇습니까- Is that so?