original_query: What were the causes of the collapse at the construction site of Line 5's Chongwenmen station?
query: What were the causes of the collapse at the construction site of Line 5's Chongwenmen station?
answer: The provided text mentions the collapse of steel beams at the construction site of Line 5's Chongwenmen station on October 8, 2003, which killed three workers and injured one, but it does not state the cause of the collapse.