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.

[EX Q]: Given Relationship: 'attack', Sentence: 'If China would choose to ever attack Taiwan , with such a huge force , the U.S. would have great difficulty repelling such a large military that could quickly overrun the Island .'
[EX A]: attack

[EX Q]: Given Relationship: 'speak at', Sentence: 'It is true that Mahmod Ahmadinejad is scheduled to speak at Columbia this Monday .'
[EX A]: speak

[EX Q]: Given Relationship: 'be head of', Sentence: 'The service has been dubbed Derivatives Collateral Net and automatically aggregates and nets the overall collateral obligations of its participants , explains Art Certosimo , executive vice president and head of Broker-Dealer Services at the bank .'
[EX A]:
head