은/ㄴ지 얼마나/ Time duration 됐다/지나다~

*은(ㄴ)지 얼마나 되다/지나다 When asking,and change 얼마나 to any Time Duration+이/가 when answering or plainly telling someone how long has it been since you did something. -This form is constructed from 은(ㄴ)지 and the verb 되다 “To become” or the verb 지나다 “To pass/elapse” -It is used to express the amount of time that has elapsed since a certain temporal point,and it can be translated as “Since” in English. 예문 브라이안한테 전화를 한지 [하(다)+ㄴ지] 삼주가 됐어요.It’s been 3 weeks” since” I called Brian. 가을 학기가 시작한지 삼 일이 지났어요.It’s been 3 days since the fall semester began. 서울에 한국어 공부하러 온지[오(다)ㄴ지] 일년 됐어요.It has been a year since I came to Seoul to study Korean. 골프를 배운지 얼마나 됐어요?How long has it been since you learned Korean? 우리가 알고 지낸지 얼마나 됐지?