1. "There is a hill from which you can look over the town."
This is grammatically correct and sounds formal. It clearly establishes that the hill provides a vantage point from which the town can be viewed.

2. "There is a hill where you can look over the town."
This is also correct and slightly less formal. Using "where" here works well in conversational English and is perfectly acceptable in both spoken and written contexts.

3. "There is a hill that you can look over the town."
This sentence is understandable but not as grammatically clear as the other two. In informal conversation, people might say it this way for simplicity, but it sounds a bit awkward. For formal or written English, the first two options are preferred.



In summary:
Formal or written use: Sentence 1 or 2 is better.
Casual spoken use: Sentence 3 is common, even if slightly informal.

홀든 콜필드 고등학교 중퇴라 가방 끈 짧아서 from which라고 써야 될 곳에 that 쓴거다
관계부사 that은 the time the place the reason the way 이런 일반화된 선행사 뒤에만 쓰는게 문법인데 병신련이라 저리 됨