Final answer:
The paragraph was revised to include the prepositional phrases for sentence variety and appropriate comma usage.
Step-by-step explanation:
Prepositional phrases in the paragraph include: 'in front of the office building', 'with jackhammers', 'throughout the city', 'in their ears', and 'around the construction site'. To encourage sentence variety and the correct use of commas, the paragraph could be rewritten as follows:
With jackhammers in hand, the construction workers demolished the concrete in front of the office building. The racket was audible throughout the city, causing people to take note. Smartly, the workers donned plugs in their ears to shield themselves from the noise. In contrast, the people around the construction site found themselves wishing for earplugs, too.