Connecting Endings -고 / -아서·어서
We often use '-고' and '-아서/어서' to connect two sentences.
-고: Listing / Sequence
'-고' lists two actions or facts side by side and can also show time order.
저는 밥을 먹고 커피를 마셔요.
jeoneun babeul meokgo keopireul masyeoyo.
I eat and drink coffee.
숙제를 하고 잤어요.
sukjereul hago jasseoyo.
I did my homework and then slept.
-아서/어서: Reason / Sequence
'-아서/어서' shows a reason or that one action leads into the next; use '-아서' after ㅏ or ㅗ, and '-어서' otherwise.
| Base | -아서/어서 | Meaning |
|---|---|---|
| 가다 | 가서 | go and / because go |
| 먹다 | 먹어서 | eat and / because eat |
| 바쁘다 | 바빠서 | because busy |
| 하다 | 해서 | do and / because |
배가 아파서 병원에 갔어요.
baega apaseo byeongwone gasseoyo.
I went to the hospital because my stomach hurt.
친구를 만나서 같이 밥을 먹었어요.
chingureul mannaseo gachi babeul meogeosseoyo.
I met a friend and we ate together.
늦게 일어나서 학교에 지각했어요.
neutge ireonaseo hakgyoe jigakhaesseoyo.
I got up late, so I was late for school.
비가 와서 우산을 샀어요.
biga waseo usaneul sasseoyo.
It rained, so I bought an umbrella.
-고 vs -아서/어서: Key Difference
'-고' simply sequences two actions that can stand apart, while '-아서/어서' links the first action tightly to the second as a cause or close sequence; compare '손을 씻고 먹어요' (then) with '손을 씻어서 깨끗해요' (because).
공원에 가서 산책했어요.
gongwone gaseo sanchaekhaesseoyo.
I went to the park and took a walk.
| Sentence | Connector | Nuance |
|---|---|---|
| 밥을 먹고 잤어요 | -고 | ate, then slept (separate) |
| 배가 고파서 먹었어요 | -아서 | hungry, so ate (cause) |
| 옷을 입고 나갔어요 | -고 | put on clothes and left |
💡 Tip: Don't add past tense to the '-아서/어서' clause: '먹었어서' is wrong, '먹어서' is correct.
💡 Tip: For commands and suggestions, use '-(으)니까' to give a reason instead of '-아서/어서', as in '바쁘니까 나중에 와요.'