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For example , vinylidene chloride yields the plastic polyvinylidene chloride ( PVDC ) ( − CCl2 − CH2 − ) n. Likewise , vinylidene fluoride gives polyvinylidene fluoride ( PVDF ) .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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