Answer:
The story of Bradbury is set in a dystopian age where books and magazines were outdated. Also, crime was non-existent and so was the need for police. The police patrol cars had now been trimmed from 3 to one.
In the city where Leonard Mead lives, people got all the entertainment they needed from their Televisions Sets.
So at night, no one walked the streets. Everyone sat at home in front of the TV except for Mead.
So to answer the first question, the streets had become like a graveyard as there was no one in the street, only quietness and occasional canine activity from dogs who would bark at noises mostly of which were his until he changed his shoes.
The tombs in the story are used as a simile. A representation of the houses that betrayed zero activity, regardless of the people in them.
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