What are common mistakes with -아/어서?

Adding past tense before -아/어서. Using -아/어서 with commands (should use -니까). Confusing with -고. EN speakers: English 'because' and 'so' don't restrict tense on the reason clause — Korean -아/어서 does. This is a frequent error. DE speakers: German 'weil' puts verb last (like Korean!) but allows tense marking. The no-past-tense rule with -아/어서 is hard. RU speakers: Russian 'потому что' allows tense on both clauses. The restriction on past tense before -아/어서 is counterintuitive. CS speakers: Czech 'protože' similarly allows tense on both. Same challenge as Russian speakers.

-아/어서: rules, examples & exercises | Korean Grammar A1

-아/어서

A1 — 연결어미

The causal/sequential connective -아/어서 (because, so, and then)

I can give reasons and describe sequences of events using -아/어서

The causal/sequential connective -아/어서 (because, so, and then)

Examples

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.

연결어미A1

Because/So (-아/어서)

The causal/sequential connective -아/어서 (because, so, and then)

Learning Goal

I can give reasons and describe sequences of events using -아/어서

Exam Skills:듣기읽기

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.

Apply this grammar in A1 course exercises

Practice Exercises

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

A1 Course

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Put it into practice

Try a free exercise from the course

Frequently asked questions

When is -아/어서 used?: The connective ending -아/어서 links a reason to a result, or shows sequence .
How is -아/어서 formed?: -아/어서 vs -고: -아/어서 implies causation or tight sequence. -고 is neutral listing.
What are common mistakes with -아/어서?: Adding past tense before -아/어서. Using -아/어서 with commands (should use -니까). Confusing with -고. EN speakers: English 'because' and 'so' don't restrict tense on the reason clause — Korean -아/어서 does. This is a frequent error. DE speakers: German 'weil' puts verb last (like Korean!) but allows tense marking. The no-past-tense rule with -아/어서 is hard. RU speakers: Russian 'потому что' allows tense on both clauses. The restriction on past tense before -아/어서 is counterintuitive. CS speakers: Czech 'protože' similarly allows tense on both. Same challenge as Russian speakers.