Adding ㅓ or ㅏ to a predicate stem
Some endings require adding ㅓ or ㅏ to a predicate stem in order to be used. We discuss how to determine which is added. First, if the predicate has any irregular rules, apply them. Then if the vowel closest to the end of the modified predicate stem is ㅏ or ㅗ then ㅏ is added to the stem, othwerwise ㅓ is added to the stem.
First, we apply any irregular rules to 바라보다. 바라보다 is not irregular so we observe the stem 바라보. The vowel closest to the end of the modified predicate stem 바라보 is ㅗ and so ㅏ will be added to the predicate stem. 바라보 becomes 바라봐.
First, we apply any irregular rules to 바쁘다. 바쁘다 is 으 irregular so ㅡ is removed from the predicate stem. 바쁘 becomes 바ㅃ. The vowel closest to the end of the modified predicate stem 바ㅃ is ㅏ so ㅏ is added to the stem. 바ㅃ becomes 바빠.
Placement of ㅓ or ㅏAfter determining whether ㅓ or ㅏ is added to the predicate's stem, the new letter may be added in one of 4 ways.
The letter may be added as a new syllable 어 or 아.
+ (ㅓ or ㅏ) = 먹어
The final vowel (if any) may change to another vowel.
+ (ㅓ or ㅏ) = 써
Letters may be removed and added to the stem.
+ (ㅓ or ㅏ) = 불러
The letter may not be added at all.
가다 + (ㅓ or ㅏ) = 가
We show examples here of common stem changes.