A group of people work on the side of a large metal structure that is very blue on a cloudy day.
The workers of the large blue metal structure that appears very blue on cloudy days
When a group of people work, they can be categorized as workers.  When people work on the side of a metal structure, it is a rephrasing to say they are workers of the metal structure.  Metal structure that appears very blue on cloudy days is a rephrasing of metal structure that is very blue on a cloudy day.
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