냈는데

In a sentence

• 나는 숙제를 다 하고 선생님께 제출했는데, 추가 설명이 필요하다고 하셨다.

  I completed my homework and submitted it to the teacher, but they said additional explanations are required.

  In this sentence, '냈는데' conveys an action of submitting something in the past and introduces a contrast or continuation to express the subsequent feedback received.

• 친구에게 생일 선물을 줬는데 매우 기뻐했어요.

  I gave a birthday gift to my friend, and they were very happy.

  Here, '냈는데' describes the action of giving a gift and sets up the following result or reaction.

• 어제 신청서를 냈는데 아직 답변이 안 왔어요.

  I submitted the application yesterday, but no reply has come yet.

  In this sentence, '냈는데' is used to state that the application was submitted in past tense and introduces the subsequent event or lack thereof.