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For years it was all but unheard of in most cities for a hospital to regularly hang out a ` ` No Vacancy ' ' sign for ambulance crews .
 most cities, a hospital, ambulance crews, ambulance
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: geographical social political, organization, person, location, facility, vehicle, weapon 
Text: {0} 
Answer:
 most cities, a hospital, ambulance crews, ambulance