떄문이다

In a sentence

• 시험에 미끄러진 이유는 충분히 공부하지 않았기 때문이다.

  The reason I failed the test is because I didn't study enough.

  The word '때문이다' is used here to explain the reason behind failing the test, linking the lack of study as the cause.

• 그 성취는 그의 끊임없는 노력 때문이었다.

  The achievement was due to his relentless efforts.

  In this sentence, '때문이다' identifies the reason for the success, highlighting continuous effort.

• 많은 사람들이 축제에 참여한 이유는 그날이 지역 공휴일이기 때문이다.

  The reason many people attended the festival is that it was a local holiday.

  Here, '때문이다' explains the cause of the participation in the festival, relating it to the local holiday.