Core Grammar Rule: -아/어서 (Reason) & -지만 (Contrast)
These two endings are essential for connecting ideas. -아/어서 links a cause to a result, while -지만 connects two contrasting facts or situations.
Meaning & Usage
-아/어서 (Reason): This pattern means "so" or "because" and connects two related clauses. The first clause is the reason or cause for the second clause.
-지만 (Contrast): This pattern means "but" or "although" and is used to connect two clauses that have opposing or contrasting content.
Conjugation Rules
-아/어서: Attach to a verb or adjective stem.
Stems ending in ㅏ or ㅗ + 아서 (e.g. 좋다 → 좋아서, 가다 → 가서).
Stems ending in other vowels + 어서 (e.g. 춥다 → 추워서, 먹다 → 먹어서).
하다 verbs → 해서 (e.g. 공부하다 → 공부해서).
-지만: Attach directly to the verb or adjective stem, regardless of whether it ends in a vowel or a consonant.
e.g. 좋다 → 좋지만, 먹다 → 먹지만, 예쁘다 → 예쁘지만.
-아/어서: 좋아서 (because it's good) / -지만: 좋지만 (it's good, but...)
Politeness & Formality
How you express reasons and contrasts changes depending on who you're talking to. Using the right level of politeness is key to natural Korean conversation.
Expressing Reasons (Polite vs. Casual)
Context: When explaining why you feel a certain way about the weather to a senior colleague, you use the polite ~아/어서 ~아요/어요 form. With a close friend, you can drop the 요 for a casual feel.
Example (Polite): 날씨가 좋아서 기분이 좋아요. (The weather is nice, so I feel good.)
Example (Casual): 날씨가 좋아서 기분이 좋아. (The weather's nice, so I feel good.)
Expressing Contrast (Polite vs. Casual)
Context: Similarly, when contrasting yesterday's weather with today's in a professional setting, use ~지만 ~아요/어요. With a friend, the casual ~지만 ~아/어 is more natural.
Example (Polite): 어제는 추웠지만 오늘은 따뜻해요. (It was cold yesterday, but it's warm today.)
Example (Casual): 어제는 추웠지만 오늘은 따뜻해. (It was cold yesterday, but it's warm today.)