보여줬던

In a sentence

• 그가 나에게 그의 그림을 보여줬던 순간을 잊을 수 없어요.

  I can't forget the moment he showed me his painting.

  Here, "보여줬던" is used to indicate an action in the past where someone showed something.

• 선생님이 학생들에게 역사적인 사진을 보여줬던 시간이 아주 의미 있었어요.

  The time the teacher showed historical pictures to the students was very meaningful.

  In this sentence, "보여줬던" refers to the act of having shown something in a meaningful context.

• 친구가 나에게 새로운 기술을 보여줬던 것이 도움이 되었어요.

  My friend showing me a new skill was helpful.

  "보여줬던" here is used to highlight an instance of demonstrating something in the past.