-아/어서 vs -(으)니까 vs -기 때문에

Mar 22

1. -아/어서

1) direct cause, reason or background

e.g. 키가 커서 바지가 짧아요. = I'm tall so the pants are short.

e.g. 시끄러워서 못 잤어요. = It was so noisy I couldn't sleep.

e.g. 날씨가 추워서 옷을 많이 입었어요 = It was cold so I wore a lot of clothes.

e.g. 한국어가 재미있어서 한국어를 배워요. = Korean is fun so I'm learning Korean.

2) first action of two related action sequences (action A is the prerequisite for action B)

e.g. 친구를 만나서 영화를 봤어요. = I met with a friend and watched a move together.

e.g. 헬스장에 가서 운동을 했어요. = I went to the gym and worked out.

e.g. 운전해서 부산에 갔어요. = I drove and went to Busan. (I drove to Busan)

e.g. 옷을 벗어서 바닥에 두지 마세요. = Don't take off your clothes and leave them on the floor.

note)

Can't be used in imperative sentences (command, suggestion, request, proposal, instruction, etc) when used for 1
Can't be conjugated in the past tense.

e.g. 친구를 만났어서 영화를 봤어요. (X)

e.g. 헬스장에 갔어서 운동을 했어요. (X)

e.g. 친구를 만나겠어서 (X)

e.g. 헬스장에 가겠어서 (X)

2. -(으)니(까)

1) often used to express the speaker's logical reasoning, judgment

e.g. 심심하니까 게임을 하는 게 어때요? Because we're bored, why don't we play a game?

e.g. 키가 그니까 농구를 잘할 것 같아요. Because he's tall, so I think he'll be good at basketball.

e.g. 아기가 자니까 조용히 얘기해주세요. Because the baby's sleeping, please speak quietly.

e.g. 비가 오니까 우산을 가져가세요. Because it's raining, please take an umbrella.

2) to express action followed by speaker's realization or discovery

e.g. 학교에 가니(까) 사람이 한 명도 없었어요. I went to school and found out that there was no one.

e.g. 직접 만나보니(까) 친절했어요. I met with him in person and found out he was actually kind.

e.g. 일을 끝내고 나니(까) 기분이 좋아졌어요. I finished the work and realized I felt better.

e.g. 듣고 보니(까) 기분이 나쁘네요. I've heard you and I'm realizing I am offended.

note)

3. -기 때문에

often used in formal settings to emphasize a cause or give an objective explanation

e.g. 저는 한국어를 아직 잘 못하기 때문에 한국 회사에 취직할 생각이 없어요. Because I'm not good at Korean yet, I'm not planning to get a job at a Korean company.

e.g. 거리가 멀기 때문에 차를 타고 갔어요. Because it's far, I drove there.

e.g. 지금 돈이 별로 없기 때문에 지출을 줄여야 돼요. Because I don't have a lot of money now, I have to reduce my spending.