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china has tested barack obama early in his presidency , with a flotilla of naval vessels surrounding and harassing a us spy ship in the south china sea .
 flotilla, vessels
Please list all entity pairs containing a certain relationship in the given options.Output format is "word1, word2; word3, word4". 
Option: component whole, NA, instrument agency, member collection, cause effect, entity destination, content container, message topic, product producer, entity origin 
Text: {0} 
Answer:
 flotilla, vessels