I was studying from TTMIK level 1 textbook and workbook present and past tense and I noticed that when a verb is changed to present or past tense, the syllable was changed to a slightly different form. For example:

보다 + 아요 => 봐요

쓰다 + 어요 => 써요

It wasn't really explained in the textbook other than it was based on the pronunciation. I don't really get how it exactly got the final form of the verbs. and is it wrong if you dont mixed the verbs and the 아요 or the 았어요 together?

Thank you <3

  • these are secial cases they dont follow the general pattern. You will just have to memorize them
    – user17915
    Jan 10 at 12:00

1 Answer 1


The changes in verb ending forms are like verb conjugations in other languages. I will mention the ones relevant to your question.

  1. vowel harmonization rules.

    Some vowels have a brighter and lighter feel, like ㅗ and ㅏ, while others have darker and heavier feel, like ㅜ and ㅓ. When we add a connective syllable 아 or 어, we choose the similar kind.

    보(다) has ㅗ in its stem, so we say 보아요 instead of 보어요, since ㅗ and ㅏ are in the same bright sounding vowels.
    먹(다) has ㅓ in its stem, so we pick 어 to make it 먹어요.

    The rules is: use 아(요) if the vowel in the last syllable of the verb stem is ㅗ or ㅏ, and 어(요) in all other cases.

    So 뽑다 -> 뽑아요, 막다 -> 막아요, 옳곧다 -> 옳곧아요, but 물다 -> 물어요, 질기다 -> 질기어요/질겨요, 춤추다 -> 춤추어요/춤춰요.

  2. Certain sequences of vowels merge together, to make them shorter and also because they don't sound very clear. There are many different cases of these, but the following are the more common ones.

    _ (as in 으) is the most light and indistinct sounding vowel, so it is usually absorbed into another vowel it comes in contact with.

    So 쓰(다) + 어요 (어 is chosen according to the #1 rule above) becomes 쓰어요, but then the ㅡ + ㅓ (since ㅇ in 어 has no sound) sequence contracts to ㅓ producing 써. So we have 써요 instead of 쓰어요. This doesn't happen if there is a consonant between the vowels, as in 쓸다 + 어요 -> 쓸어요.

    Secondly, repeated vowels contract to single vowel, so 가다 + 아요 -> 가요, not 가아요.

    The ㅗ + ㅏ sequence in 보아요 can contract to ㅘ, so we more often say 봐요 than 보아요, although both are correct.
    Similarly, ㅜ + ㅓ contracts to ㅝ, as in 무거워요 (무겁(다) + 어요 -> 무겁어요 -> 무거우어요 (irregular conjugation that changes ㅂ to 우) -> 무거워요 (ㅜ+ㅓ -> ㅝ).

    And there is the important case of 하다 which becomes 하여요 or 해요 (more common). This is another special case arising from phonetic reasons.

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