Part of the Korean Whodunit grammar series · Korean reviewed by native speakers
Past tense is where a story locks into time. In Korean, one vowel decides whether something happened — and a single mismatched ending can quietly move a speaker from bystander to witness to suspect.
To make a verb past tense, take the stem and add 았어요 if the stem’s final vowel is ㅏ or ㅗ, and 었어요 for every other vowel. The vowels contract in speech, which is why it sounds smooth.
to go → went. Stem 가- has ㅏ, so 았어요, contracted to 갔어요.
to eat → ate. Stem 먹- has ㅓ, so 었어요.
The 하다 verbs are their own family: 하다 becomes 했어요 ("did"). You will use it constantly — 공부했어요, 일했어요, 사랑했어요.
The gap between 가요 ("go / am going") and 갔어요 ("went") is a single tense marker, but it changes when the action lives. Get it wrong and you claim to be doing now what you actually did yesterday.
A witness who answers 저는 그 방에 안 가요 ("I don’t go to that room") when asked about last night has answered a different question than the one asked. Present tense dodges the past. In an interview transcript, a speaker who keeps sliding into the present to avoid a past-tense admission is telling you where to look.
A few stems shift before the past ending. ㄷ-irregular verbs like 듣다 ("listen") become 들었어요; ㅂ-irregulars like 춥다 ("cold") become 추웠어요; and ㅡ drops, so 쓰다 ("write") becomes 썼어요. These are not exceptions to fear — they are the handful you will meet daily.
to listen → listened. The ㄷ softens to ㄹ before the past ending.
Tense is timeline. In a case, the difference between "I go" and "I went" can be the difference between an alibi and a confession.
In The Red-Stained Script, the timeline is everything — and the verbs carry it. Read the evidence and watch the tenses. Free, no sign-up.
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