Just did: -ㄴ/은 지

At its core, -ㄴ/은 지 functions as a bound noun construction. The little word 지 specifically represents the "passage of time." When you attach it to a verb, you're essentially creating a phrase that means "the time since [doing something]." Because 지 is a noun here, it usually needs a friend to finish the sentence. Most of the time, that friend is the verb 되다 (to become/to pass). You’ll say things like "The time since I ate is three hours" or 밥을 먹은 지 세 시간이 됐어요. It sounds a bit robotic when translated literally, but in Korean, it's perfectly natural and smooth. You can also use other verbs like 넘다 (to exceed) or 안 되다 (to not be that long yet) to add more flavor. It's like a grammar traffic light; it tells you exactly where you are on the timeline of your life.

1. 1Setting this up is easier than choosing a Netflix show on a Friday night. Just follow these steps:
2. 2Identify the Verb Stem: Take your verb and drop the 다.
3. 3Check the Ending: Look at the last character of the stem.
4. 4Vowel or ㄹ Ending: Attach -ㄴ 지. If the stem ends in ㄹ, drop the ㄹ first then add -ㄴ 지. (Example: 가다 → 간 지, 살다 → 산 지).
5. 5Consonant Ending: Attach -은 지. (Example: 먹다 → 먹은 지).
6. 6Add the Time and Verb: Follow up with a duration and a verb like 되다. (Example: 한 달 됐어요).
7. 7CRITICAL TIP: Always put a space before 지. In Korean, 간지 (no space) is slang for "cool/style," while 간 지 (with space) means "since I went." Unless you want to tell someone your "going style" is three hours long, keep that space!

Use this whenever you need to quantify the gap between "then" and "now."

• Social Catch-ups: "It's been a long time since we met!" 우리 만난 지 오래됐어요!
• Health and Habits: "It's been two weeks since I quit coffee." (Yes, we've all been there, and yes, the headache is real).
• Job Interviews: "I've been studying marketing for five years." 마케팅을 공부한 지 5년 됐어요.
• Travel: "How long has it been since you arrived in Seoul?"
• Milestones: Celebrating 100 days since you started dating someone (a huge deal in Korea!).

This isn't a "one size fits all" accessory.

• Adjectives are a No-Go: You can't usually use this with adjectives like 예쁘다 (pretty) or 춥다 (cold). You can't say "It's been three days since it was cold" using this specific pattern. It's strictly for actions.
• Future Events: This looks backward, not forward. You can't use it to say "It will be three days until my birthday."
• Continuous States: If the action is still actively happening without a break (like "I have been tall for 10 years"), it doesn't fit. It measures the time *after* an action started or happened.

1. 1The Spacing Trap: As mentioned before, 먹은지 is wrong. 먹은 지 is right. Native speakers might get lazy in KakaoTalk, but for your exams and formal writing, that space is non-negotiable.
2. 2Confusing with -ㄴ지 (Indirect Questions): There is another grammar point -ㄴ/은/는지 used for things like "I don't know if..." (e.g., 누구인지 몰라요). That one doesn't have a space and doesn't involve time. If you see a duration (hours, days, years) nearby, you're dealing with our time-elapsed friend.
3. 3Incorrect Particles: Sometimes people try to put 가/이 or 를 after 지. While 지 가 is technically possible in some rare emphasis cases, stick to 지 + [Time] + 되다 for 99% of your conversations.

• -ㄴ/은 지 vs. -ㄴ 후에 (After): -ㄴ 후에 just means "after doing A, I did B." It doesn't care about the duration. -ㄴ/은 지 is obsessed with the clock. It focuses entirely on *how long* that gap is.
• -ㄴ/은 지 vs. -기 시작하다 (Start doing): If you say 공부하기 시작했어요, you are focusing on the moment you opened the book. If you say 공부한 지 한 시간 됐어요, you are complaining (or bragging) about the 60 minutes that have passed since then.
• -아/어 있다 vs. -ㄴ/은 지: The former focuses on a state (e.g., "is sitting"). Our grammar point focuses on the time elapsed since the act of sitting down occurred.