Because/So (-아/어서)
The causal/sequential connective -아/어서 (because, so, and then)
I can give reasons and describe sequences of events using -아/어서
Look at these examples. Can you spot the grammar pattern?
피곤해서 일찍 잤어요.
I went to bed early because I was tired.
비가 와서 집에 있었어요.
It rained, so I stayed home.
시장에 가서 과일을 샀어요.
I went to the market and bought fruit.
만나서 반갑습니다.
Nice to meet you.
Pay attention to the highlighted parts. What do they have in common?
-아/어서 (Because / So / And then)
The connective ending -아/어서 links a reason to a result, or shows sequence.
| Stem vowel | Form | Example |
|---|---|---|
| ㅏ, ㅗ | -아서 | 작다 → 작아서 (because it's small) |
| other | -어서 | 먹다 → 먹어서 (after eating) |
| 하다 | 해서 | 피곤하다 → 피곤해서 (because tired) |
Two main uses:
| Use | Example | Translation |
|---|---|---|
| Reason | 배가 아파서 못 먹어요. | I can't eat because my stomach hurts. |
| Sequence | 집에 가서 쉴 거예요. | I'll go home and (then) rest. |
Key rules:
- NEVER put past tense on the -아/어서 clause: *피곤했어서 (WRONG) → 피곤해서 (RIGHT)
- Cannot use with imperative/propositive: *배가 아파서 약을 드세요 (WRONG) → 배가 아프니까 약을 드세요 (RIGHT, use -니까)
-아/어서 vs -고: -아/어서 implies causation or tight sequence. -고 is neutral listing.
Add past tense before -아/어서 (forbidden). Use with commands (use -니까 instead).
Common Error Patterns
Put past tense marker on -아/어서 clause
NEVER use past tense before -아/어서: 피곤해서 (not *피곤했어서). Tense is on the main clause only
Used -아/어서 with imperative or propositive
Use -니까 instead of -아/어서 before commands: 추우니까 문을 닫으세요 (not *추워서 닫으세요)
피곤해서 일찍 잤어요.
I went to bed early because I was tired.
피곤하다 → 피곤해서 (because tired). Note: NO past tense on 피곤하다 even though this happened in the past.
비가 와서 집에 있었어요.
It rained, so I stayed home.
오다 → 와서 (because/since it came = rained). Reason (rain) → result (stayed home).
시장에 가서 과일을 샀어요.
I went to the market and bought fruit.
가다 → 가서 (went and then). Sequential use — go first, then buy. Implies tight connection between actions.
만나서 반갑습니다.
Nice to meet you.
만나다 → 만나서 = having met (you), I'm glad. A set phrase using -아/어서.
Practice in course
Apply this grammar in A1 course exercises