The plural form of roof is roofs.
Although there are many words where f would become v, like in hooves, this is not one of those cases.
“The ship was as still as SHE could be” , they are personifying the ship as a she when it is not a living person
If Zack is like the alienated workers interviewed in Terkel’s (1974) classic study, he would most likely describe himself as a <span>"cog in a faceless machine of industry."
This also refers to the fact that there is no individuality involved here - all workers are the same, there is no difference between them, and they are treated as if they were just elements needed to complete a system, and not as real humans.
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