Connectors Are the Intermediate Threshold
At beginner level you string short sentences together. At intermediate level you link them, and that is what TOPIK II and real conversation reward. Korean connectors attach to the verb stem and carry both meaning and register.
Most connectors replace the tense ending, so the tense appears only on the final verb of the sentence.
Adding and Sequencing: -고
The most common connector. It lists actions or facts without implying cause, and it can chain several clauses.
-고 does not mean because
아파고 is not "because I am sick". For cause use -아서/어서 or -(으)니까. Confusing the two is one of the most frequent intermediate errors.
Contrast: -지만 and -는데
-는데 does three jobs
It gives background before a request, softens a disagreement, and sets up a mild contrast. Learners often avoid it because it has no single English equivalent, which is exactly why it sounds so natural in Korean.
Cause: -아서/어서 and -(으)니까
Both mean because, but they are not interchangeable. The difference is what follows the clause.
The Rest of the Set
Learn these in pairs that contrast: -(으)면 versus -(으)니까, -고 versus -아서, -지만 versus -는데. Contrast is what fixes them in memory.
Errors That Mark a Learner
Practice
Join each pair with the connector in brackets.
- 비가 와요. 집에 있어요. (-아서/어서)
- 비싸요. 좋아요. (-지만)
- 지금 바빠요. 이따가 전화하세요. (-(으)니까)
- 음악을 들어요. 공부해요. (-면서)
- 시간이 있어요. 와 주세요. (-(으)면)
These connectors are half of the TOPIK writing score — see questions 53 and 54 — and they pair naturally with negation.
FAQ
What is the difference between -아서 and -(으)니까?
Both mean because, but -아서/어서 cannot be followed by a request or suggestion, while -(으)니까 can. So 비가 와서 우산을 썼어요 is fine, but a request needs 비가 오니까 우산을 가져가세요.
Why do I keep hearing -는데?
Because it is the most versatile connector in Korean. It provides background, softens a request, and sets up mild contrast, so it appears constantly in natural speech and is often described as having no direct English translation.
Do I put the tense on every clause?
No. Attach the connector to the plain stem and put the tense on the final verb: 밥을 먹고 영화를 봤어요, not 먹었고 봤어요. Some connectors such as -았/었더니 encode their own time relationship.
How many connectors should I learn?
Around ten cover most intermediate speech and writing: -고, -지만, -는데, -아서, -(으)니까, -(으)면, -면서, -거나, -(으)려고 and -기 때문에. Add more as you meet them in reading rather than memorising a long list.