From the given sentence, extract the phrase (often noun or verb) that carries the given relationship. The generated phrase should be present in the sentence.
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Question: Given Relationship: 'be president of', Sentence: 'Barack Obama today becomes the first black president of the United States of America .'

Answer: president


Question: Given Relationship: 'be son of', Sentence: 'She married Major Arthur William Fitz Roy Somerset , son of Field Marshal FitzRoy James Henry Somerset , 1st Baron Raglan , on 8 July 1845 .'

Answer: son


Question: Given Relationship: 'run on', Sentence: 'Skype for Pocket PC 1.0 enables cross-platform voice calls to other Skype users running Skype for Windows , Skype for Linux , or Skype for Mac OS X .'

Answer:
running