The Boundary Between Regular and Irregular Conjugation

The regular system learned in this course explains many forms, including common vowel contractions and ㅡ deletion.

Some forms, however, cannot be predicted from those rules alone. In those cases, a separate irregular pattern is involved.

The goal of this lesson is only to recognize that boundary, not to learn how each irregular form is generated.

Compare 닫다 → 닫아요 and 믿다 → 믿어요 with 듣다 → 들어요 and 걷다 → 걸어요 .

The first pair follows the regular principles learned in this course. The second pair produces forms that those basic principles alone do not predict.

Do not classify a word from its final ㄷ alone because not every ㄷ-final verb follows the same pattern. The generation rule is covered in the Irregular Conjugation course.

Compare 입다 → 입어요 and 좁다 → 좁아요 with 춥다 → 추워요 and 덥다 → 더워요 .

The regular rules explain the first pair, but they do not fully predict the second pair.

A final ㅂ by itself does not tell you whether a word follows a regular or irregular pattern. The detailed generation rule is covered separately.

쓰다 → 써요 is explained by the regular ㅡ-deletion pattern learned earlier. By contrast, 모르다 → 몰라요 and 빠르다 → 빨라요 are not predicted by applying that same rule alone.

These examples belong to a separate irregular pattern whose generation process is outside this course.

First apply the regular rules learned in this course, including common vowel contraction and ㅡ deletion.

If a form such as 들어요 , 추워요 , or 몰라요 still cannot be explained, treat it as an irregular-pattern candidate rather than inventing a new rule. Check its dictionary form and continue in the Irregular Conjugation course.