매트리스

In a sentence

• 새 매트리스를 구입했어요.

  I bought a new mattress.

  In this sentence, '매트리스' is used as the subject being the object purchased.

• 매트리스가 너무 딱딱해서 불편해요.

  The mattress is too hard, so it's uncomfortable.

  Here, '매트리스' is describing the object that has the attribute of being hard.

• 침대 위에 매트리스를 바꿔 놓았어요.

  I replaced the mattress on the bed.

  In this usage, '매트리스' refers to the object that was swapped in term of location.