누군가가

In a sentence

• 누군가가 창문을 열어 두었어요.

  Someone left the window open.

  누군가가 is used here as the subject of the sentence, indicating an unspecified person who performed the action of leaving the window open.

• 누군가가 내 물건을 가져갔어요.

  Someone took my belongings.

  Here, 누군가가 serves as the subject to refer to an unknown individual who took the belongings.

• 나는 누군가가 나를 보고 있는 것을 느꼈어요.

  I felt that someone was watching me.

  In this sentence, 누군가가 functions to introduce the subject of a subordinate clause, describing an unspecified person performing the action of watching the speaker.