one of the saddest sights in this world isthatof a young man who has sacrificed what little health and constitution he had on account of the hard struggle for existence.대명사 that이 뭘 가리키는 거죠?that of 안쓰고 그냥 is 다음에 a young man who~ 이렇게 쓰면 안되나요?답변부탁드립니다.