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Potomac Airfield , also known as Potomac Airport or Potomac Airpark , is a privately owned , public-use airport located in the community of Fort Washington ( formerly known as Friendly ) , in Prince Georges County , Maryland , United States ( just outside Washington , D.C. ) .
 location: Prince Georges County; location: Maryland; location: United States; location: Washington , D.C.
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 location: Prince Georges County; location: Maryland; location: United States; location: Washington , D.C.