it was a cold winter morning in a busy subway station. there, clothed in jeans, and a t-shirt, was a young man playing his violin with great passion. he played for almost an hour, during which time at least a thousand people must have passed by.

문장 분석좀 부탁드려요~ 특히 which가 왜 나오며 무엇으로 사용된 것인가요?