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.

Given Relationship: 'attack', Sentence: 'The U.S. has pledged to warn Israel of any attack against Iraq .'
attack

Given Relationship: 'be focus of', Sentence: 'The Glaucoma Research Center at Wills Eye Institute focuses and coordinates these efforts to discover and disseminate sight-saving knowledge around the world .'
focuses

Given Relationship: 'be wife of', Sentence: 'Michelle Obama , wife of Democratic Presidential candidate Barack Obama , acknowledges the crowd at the Democratic National Convention 2008 at the Pepsi Center in Denver , Colorado , on August 25 , 2008 .'

wife