한다고

In a sentence

• 그가 열심히 공부한다고 들었어요.

  I heard that he studies hard.

  In this sentence, "한다고" introduces reported speech, indicating the act of studying by the third person.

• 나는 밤늦게까지 일한다고 저녁을 거릅니다.

  I skip dinner because I work late at night.

  Here, "한다고" explains the reason for skipping dinner, describing an ongoing action.

• 친구는 운동한다고 핑계를 댔어요.

  The friend made an excuse by saying they were exercising.

  In this case, "한다고" is used to indicate what the friend's excuse was about, an expression of intention or claim.