Contractions in the Past (오다 → 왔어요, 마시다 → 마셨어요) | Korean Grammar

If the present-tense vowel contractions felt like a lot to absorb — 오 + 아 → 와, 주 + 어 → 줘, 마시 + 어 → 마셔 — here is the reward: you never have to learn them a second time for the past. The past tense marker -았/었- clips onto the exact same fused stem you already say in the present. There is one clean move to internalize, and this page drills it until it is automatic.

The one move: polite present stem + ㅆ받침

Take any verb in its 해요체 present form, strip the final 요, and add a ㅆ 받침 plus -어요. That is the whole past tense.

와요 → 와 + ㅆ + 어요 → 왔어요
봐요 → 봐 + ㅆ + 어요 → 봤어요
줘요 → 줘 + ㅆ + 어요 → 줬어요
돼요 → 돼 + ㅆ + 어요 → 됐어요

Because the contraction already happened when you built the present, there is nothing left to fuse. The vowel is settled; you are only stacking a ㅆ받침 under it. This is why re-deriving the past "from the dictionary form" is wasted effort — you already did the hard part.

어제 친구가 집에 왔어요.

eoje chinguga jibe wasseoyo

A friend came over to my place yesterday.

주말에 영화를 봤어요.

jumare yeonghwareul bwasseoyo

I watched a movie over the weekend.

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Say it as a recipe: present -아/어 form, plus ㅆ. If you can already say 와요 / 봐요 / 줘요 / 돼요, then 왔어요 / 봤어요 / 줬어요 / 됐어요 come for free. Never build the past by re-fusing vowels from scratch — that is where the errors live.

Identical-vowel stems: 가 → 갔어요, 서 → 섰어요

A stem whose vowel already matches the harmony vowel merged to nothing in the present (가 + 아 → 가), so the past just adds ㅆ under that single vowel.

아침 일찍 회사에 갔어요.

achim iljjik hoesae gasseoyo

I went to the office early in the morning.

버스가 갑자기 멈춰 섰어요.

beoseuga gapjagi meomchwo seosseoyo

The bus suddenly came to a stop.

Here 가요 → 갔어요 and 서요 → 섰어요. The vowel never doubles up — you write 갔-, not ×가았-. English speakers sometimes feel that a "bigger" past tense needs a fuller stem, but the fused vowel is the whole stem, and the past is simply that stem carrying a ㅆ.

ㅗ rounds into ㅘ: 오다 → 왔어요, 보다 → 봤어요

A ㅗ-stem fused to ㅘ in the present (오 + 아 → 와), so the past is 왔-, 봤-, and so on.

택배가 오늘 아침에 왔어요.

taekbaega oneul achime wasseoyo

The package came this morning.

아까 마트에 가서 우유를 사 왔어요.

akka mateue gaseo uyureul sa wasseoyo

I went to the store earlier and bought some milk.

그 드라마 지난주에 다 봤어요.

geu deurama jinanjue da bwasseoyo

I finished watching that drama last week.

Dictionary	Present	Past	Reading
오다 (come)	와요	왔어요	wasseoyo
보다 (see/watch)	봐요	봤어요	bwasseoyo
쏘다 (shoot)	쏴요	쐈어요	sswasseoyo

ㅜ rounds into ㅝ: 주다 → 줬어요, 배우다 → 배웠어요

A ㅜ-stem fused to ㅝ in the present (주 + 어 → 줘), and the past keeps that ㅝ under a ㅆ.

동생한테 용돈을 조금 줬어요.

dongsaenghante yongdoneul jogeum jwosseoyo

I gave my younger sibling a little pocket money.

작년부터 한국어를 배웠어요.

jangnyeonbuteo hangugeoreul baewosseoyo

I've been learning Korean since last year.

Notice 배웠어요 packs three syllables of history into one tail: 배우 + 었 fused to 배웠. If you can say the present 배워요, the past is just 배웠-.

ㅣ glides into ㅕ: 마시다 → 마셨어요, 기다리다 → 기다렸어요

A stem ending in ㅣ glided into 어 to make ㅕ in the present (마시 + 어 → 마셔), so the past is 마셨-, 기다렸-, and so on. This is one of the highest-yield patterns because so many everyday verbs end in 이/리/시.

목이 말라서 물을 다 마셨어요.

mogi mallaseo mureul da masyeosseoyo

I was thirsty, so I drank all the water.

카페에서 친구를 한참 기다렸어요.

kapeeseo chingureul hancham gidaryeosseoyo

I waited a good while for my friend at the café.

ㅚ becomes ㅙ: 되다 → 됐어요 — and the 됬 trap

되다 fuses to 돼 in the present (되 + 어 → 돼), so the past is 됐어요. This is the single most-misspelled past form in the language, so it earns its own warning.

준비 다 됐어요?

junbi da dwaesseoyo?

Is everything ready?

벌써 밤 열두 시가 됐어요.

beolsseo bam yeoldu siga dwaesseoyo

It's already twelve at night.

The spelling logic: the past needs 되 + 었, and 되 + 었 contracts to 됐 (the same fusion that turns 되어 into 돼). The wrong spelling ×됬 tries to bolt a ㅆ straight onto 되 with no 었 underneath it — but there is no vowel there to carry the past, so ×됬어요 is simply not a possible spelling.

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Test it by pulling the contraction apart: 됐 = 되었, so it is legal. ×됬 = 되 + ㅆ with nothing in between, so it is not. Whenever you are unsure whether to write 돼/됐 or 되/됬, expand it: if 되어/되었 fits, use 돼/됐; if only 되 fits, use 되. Write 됐어요, never ×됬어요.

How this differs from English

English builds its past by editing the base form — walk → walked, see → saw, give → gave — so learners instinctively reach back to the Korean dictionary form (보다, 주다) and try to transform that. In Korean the past attaches not to the dictionary stem but to the already-fused polite present. The productive base is 봐, not 보; 줘, not 주. Reach for the wrong base and you produce the two classic errors below. The reframing that fixes it: in Korean, the present 해요 form is the launchpad for almost everything — the past, the connectives, the negatives — so master it once and stop re-deriving.

Common Mistakes

1. Un-contracting the ㅗ-stem past. The past is built on the fused 와/봐, so it is 왔어요/봤어요 — never ×오았어요/×보았어요.

❌ 어제 친구가 집에 오았어요.

Wrong — the past is built on the fused 와, giving 왔어요, not ×오았어요.

✅ 어제 친구가 집에 왔어요.

eoje chinguga jibe wasseoyo

A friend came over to my place yesterday.

2. Un-contracting the ㅜ-stem past. Same trap on 주다 and its family: the base is 줘, so the past is 줬어요, not ×주었어요 in speech.

❌ 동생한테 용돈을 주었어요.

Reads like sounding it out off the page — everyday speech fuses it to 줬어요.

✅ 동생한테 용돈을 줬어요.

dongsaenghante yongdoneul jwosseoyo

I gave my younger sibling some pocket money.

3. Misspelling the past of 되다 as ×됬어요. Expand it: 됐 = 되었 is legal; ×됬 has no vowel for the tense.

❌ 이제 시간이 다 됬어요.

Wrong spelling — there is no 었 under 되; it must be 됐어요 (= 되었어요).

✅ 이제 시간이 다 됐어요.

ije sigani da dwaesseoyo

Time's up now.

4. Doubling the vowel on an identical-vowel stem. 가요 → 갔어요, not ×가았어요; 서요 → 섰어요, not ×서었어요.

❌ 오늘 아침에 회사에 가았어요.

Wrong — ㅏ + 아 already merged, so the past is just 갔어요.

✅ 오늘 아침에 회사에 갔어요.

oneul achime hoesae gasseoyo

I went to the office this morning.

Key Takeaways

The past adds a ㅆ받침 + 어요 to the fused polite-present stem you already know: 와요 → 왔어요, 봐요 → 봤어요, 줘요 → 줬어요, 돼요 → 됐어요.
Identical vowels stay merged: 가요 → 갔어요, 서요 → 섰어요 (never ×가았-).
ㅗ → ㅘ: 오다 → 왔어요, 보다 → 봤어요. ㅜ → ㅝ: 주다 → 줬어요, 배우다 → 배웠어요.
ㅣ → ㅕ: 마시다 → 마셨어요, 기다리다 → 기다렸어요. ㅚ → ㅙ: 되다 → 됐어요.
Spell the past of 되다 as 됐어요 (= 되었어요), never ×됬어요.
Do not re-derive the past from the dictionary form — the contractions transfer intact from the present.

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