I. -서 (-seo) is a non-final ending that we use when one subject performs one action and then another action. We can translate it as, “(verb1) and (verb2).” And as the order suggests, the verbs occur in the order they appear in the sentence.
II. In addition to doing two actions at once, we can use -서 (-seo) to indicate cause or reason. In this usage, it almost always requires a descriptive verb before -서 (-seo). We can translate this as, “(verb1) so (verb2).” We express tense and negation in (verb 2).
I. We use -아서 (-eoseo) with verbs that have a either the vowel ㅗ (o) or ㅏ (a) in the verb stem’s final syllable.
- 가다 (gada) “to go”
가 (ga) – verb stem
- 오다 (oda) “to come”
오 (o) – verb stem
Note: We often fuse -아 (-a) in -아서 (-aseo) into verb stems if the verb stem doesn’t end in a consonant.
II. We use -어서 (-aseo) with verbs that have any vowel other than the vowels ㅗ (o) or ㅏ (a) in the verb stem’s final syllable.
- 늦다 (neutda) “to be late”
늦 (neut) – verb stem
- 크다 (keuda) “to be big”
크 (keu) – verb stem
Note:We often fuse -어 (-eo) in -어서 (-eoseo) into verb stems if the verb stem doesn’t end in a consonant.
III. We use -여서 (-yeoseo) with 하다 (hada) verbs.
Note: We fuse -여 (-yeo) in -여서 (-yeoseo) into 하 (ha) – the verb stem of 하다 (hada). This results in 해 (hae).
- Example Sentences
- 앉아서 먹어요. (anjaseo meogeoyo.) “Sit and eat.”
(앉다) + (먹다) – (anta) + (meokda) – “sit” + “eat”
앉 (anj) – verb stem
앉 + 아서 (anj + seo)
앉아서 + 먹다 (anjaseo + meokda)
“Sit and eat.”
- 집에 와서 잤어요. (jip-e waseo jasseoyo.) “I came home and slept.”
(오다) + (자다) – (oda) + (jada) – “to come” + “to sleep”
오 (o) – verb stem
오 + 아서 – (o + aseo)
와서 (waseo) +자다 (jada)
집에 와서 잤어요.
“I came home and slept.”
Use #2bogo sipeoseo jeonhwahaesseoyo.) “I missed you, so I called.” (“I called because I missed you.”)
(보고 싶다) + (전화하다) – (bogo sipda) + (jeonhwahada) – “to miss (someone)” + “to call”
보고 싶 (bogo sip) – verb stem
보고 싶 + 어서 (bogo sip + eoseo)
보고 싶어서 전화했어요.
bogo sipeoseo jeonhwahaesseoyo.
- “I missed you, so I called.” (“I called because I missed you.”)
- 피곤해서 집에 갔어요. (pigonhaeseo jib-e gasseoyo.) “I was tired, so I went home.” (“I went home because I was
(피곤하다) + (가다) – (pigonhada) + (gada) – “to be tired” + “to go”
피곤하 (pigonha) – verb stem
피곤하 + 여서 (pigonha + yeoseo)
피곤해서 (pigonhaeseo) +가다 (gada) – “to go”
피곤해서 집에 갔어요.
pigonhaeseo jib-e gasseoyo.
“I was tired, so I went home.” (“I went home because I was tired.”)
For situations in which you make suggestions as to what to do and say -자 or -ㅂ시다, you use -(으)니까, and can’t use -아/어/여서.
- Incorrect:오늘은 추워서, 집에 있자
- Correct:오늘은 추우니까, 집에 있자
For situations in which you connect two separate actions in logical order and say, “I did XX because I did YY,” you can use both -기 때문에 and -아/어/여서.
However, when you are apologizing for a past action, you can’t say -기 때문에, but must use -아/어/여서 + 죄송합니다/미안해요/미안해.
- Incorrect:늦게 왔으니까 미안해.
- Correct:늦게 와서 미안해.