How do I use the Korean verb ending -더니 (-deoni)?

The Korean verb ending -더니 (-deoni) is used to express a cause-and-effect relationship. It indicates that the action or situation described in the first clause serves as a cause or reason for the action or situation in the second clause. This ending is often used to convey unexpected or contrasting developments. Here's how you can use it in sentences:

Basic Structure:

1. Verb/Adjective + -더니:

   • This form is used after a verb or an adjective.

2. Examples:

   • 비가 오더니 길이 많이 젖었어. (Biga odeoni giri mani jeojeosseo.)
     • It rained, and as a result, the road got very wet.
   • 일찍 나왔더니 버스가 늦게 왔어. (Iljjig nawassdeoni beoseuga neujge wasseo.)
     • I left early, but the bus came late unexpectedly.

Additional Tips:

• Casual and Polite Speech: Like many verb endings, -더니 can be used in both casual and polite speech. If you want to make it more polite, you can add 요 (yo) at the end.

• Usage with Adjectives: It can be used with adjectives as well, indicating a cause-and-effect relationship between two states or conditions.

Examples:

1. Verb:

   • 밥을 먹더니 배가 부르다. (Bab-eul meogdeoni baega bureuda.)
     • After eating, I feel full.
   • 춥더니 옷을 두껍게 입었어. (Chugdeoni os-eul duggeopge ibeosseo.)
     • Because it was cold, I wore thick clothes.

2. Adjective:

   • 피곤하더니 자는 게 좋겠다. (Pigonhadeoni janeun ge johgessda.)
     • Since I'm tired, it would be good to sleep.
   • 이렇게 늦게까지 공부하더니 머리가 아프다. (Ileohge neutgekkaji gongbuhadeoni meoriga apeuda.)
     • After studying until this late, my head hurts.

Conversation Examples:

1. Casual:

   • A: 왜 이렇게 서둘러 나오냐? (Wae ileohge seodulleo naonya?)
     • A: Why did you come out in such a hurry?
   • B: 놀랐데니 시간이 없어서. (Nollattdeoni sigani eops-eoseo.)
     • B: I was surprised, so I don't have time.

2. Polite:

   • A: 왜 그렇게 급하게 나왔어요? (A: Wae geuleohge geuphage nawass-eoyo?)
     • A: Why did you come out in such a hurry?
   • B: 비가 오더니 우산을 가져오지 않아서요. (B: Biga odeoni usan-eul gajyeo-oji anhaseoyo.)
     • B: It rained, so I didn't bring an umbrella.

Additional Phrases:

1. Unexpected Result:

   • 길게 걷더니 다리가 아프다. (Gilge geodddeoni daliga apeuda.)
     • I walked for a long time, and as a result, my legs hurt.
   • 많이 먹더니 배가 아프다. (Mani meokdeoni baega apeuda.)
     • I ate a lot, and now my stomach hurts.

2. Contrasting Situations:

   • 일찍 일어나더니 지각했어. (Iljjig ileonadeoni jikaghaess-eo.)
     • Although I woke up early, I ended up being late.
   • 비가 오더니 날씨가 갑자기 추워졌어. (Biga odeoni nalssi-ga gabjagi chuwosyeoss-eo.)
     • It rained, and suddenly the weather became cold.

Using -더니 allows you to express unexpected or contrasting outcomes by highlighting the cause-and-effect relationship between two clauses. It adds nuance to your statements by showing the surprising or consequential nature of the events you are describing.