선배들이

선배들이

"선배들이" means "seniors" or "older members" (plural) in a group or organization.

Here, '선배들이' (the seniors) acts as the subject of the sentence.

선배들이 책을 빌려주었어요.

The seniors lent a book.

In this sentence, '선배들이' refers to the seniors who are the doers of the action within the relative clause '가르쳐준'.

나는 선배들이 가르쳐준 내용을 복습했습니다.

I reviewed the material that the seniors taught me.

Here, '선배들이' conveys the seniors as the agents who organized the event, modifying '행사'.

우리는 선배들이 조직한 행사에 참가할 예정입니다.

We plan to attend the event organized by the seniors.