Past tense: 았어요 / 었어요 / 했어요

Korean past tense is made by adding a past marker to the verb stem before the polite ending 요. In everyday polite speech, the main past-tense endings you need first are 았어요, 었어요, and 했어요.

You already know polite present forms such as 가요 meaning “go”, 먹어요 meaning “eat”, and 공부해요 meaning “study”. In the past tense, these become 갔어요 meaning “went”, 먹었어요 meaning “ate”, and 공부했어요 meaning “studied”.

The choice depends mainly on the final vowel of the verb stem. If the stem has ㅏ or ㅗ, the past form usually uses 았어요. If it has another vowel, it usually uses 었어요. If the verb ends in 하다, it becomes 했어요.

For Vietnamese learners, this is easier than English in one way: Korean does not change the verb depending on the subject. 저는 갔어요, 친구는 갔어요, and 우리는 갔어요 all use the same verb form 갔어요.

When the final vowel of a verb stem is ㅏ or ㅗ, Korean usually forms the past tense with 았어요. This is why 가다 becomes 갔어요, and 보다 becomes 봤어요.

Start from the dictionary form. Remove 다 to get the stem. 가다 becomes 가. Add 았어요, and the vowels combine: 가 + 았어요 becomes 갔어요. In the same way, 보다 becomes 보 + 았어요, which naturally contracts to 봤어요.

This contraction is normal, not optional in natural speech. Koreans usually say 갔어요, not 가았어요, and 봤어요, not 보았어요 in ordinary conversation.

Common verbs in this group include 가다 to go, 오다 to come, 보다 to see or watch, 사다 to buy, and 만나다 to meet. These verbs are extremely useful because they describe basic daily actions.

When the final vowel of a verb stem is not ㅏ or ㅗ, Korean usually forms the past tense with 었어요. This includes many common verbs such as 먹다 to eat, 읽다 to read, 마시다 to drink, and 쉬다 to rest.

For example, 먹다 becomes 먹었어요. The stem is 먹, and you add 었어요. 읽다 becomes 읽었어요. 쉬다 becomes 쉬었어요.

Some verbs contract in natural speech. 마시다 becomes 마셨어요, not usually 마시었어요. This happens because 시 + 었어요 naturally combines into 셨어요.

Do not worry if the contractions feel difficult at first. The most important beginner goal is to recognize the past-tense sound 었어요 and connect it with completed actions: ate, read, drank, rested, listened, or wore.

Many useful Korean verbs are made with a noun plus 하다, such as 공부하다 to study, 일하다 to work, 운동하다 to exercise, 전화하다 to call, and 요리하다 to cook.

In the polite present tense, 하다 becomes 해요. In the polite past tense, it becomes 했어요. So 공부하다 becomes 공부했어요, 일하다 becomes 일했어요, and 운동하다 becomes 운동했어요.

This pattern is extremely productive. Once you know the noun part, you can often create a useful verb by adding 하다. For example, 청소 means cleaning, so 청소하다 means to clean, and 청소했어요 means cleaned.

For learners, 하다 verbs are one of the fastest ways to expand Korean sentence ability. You can talk about studying, working, exercising, calling, cooking, cleaning, preparing, and many more actions with the same past-tense pattern.

Past-tense questions in polite Korean are easy because the written form is almost the same as a statement. 먹었어요 means “ate”, and 먹었어요? means “Did you eat?” The question is shown by intonation and the question mark.

Useful past-time words include 어제 yesterday, 지난주 last week, 작년 last year, 아까 a short while ago, and 방금 just now. These words make the past meaning clear even before the verb appears.

A very common question is 어제 뭐 했어요?, meaning “What did you do yesterday?” The word 뭐 means “what”. The verb 했어요 comes from 하다, meaning “did”.

When answering, you can combine the patterns from this chapter: 친구를 만났어요, 영화를 봤어요, 집에서 쉬었어요, or 한국어를 공부했어요. This is enough to talk about simple past experiences in daily life.