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: 'be key to', Sentence: 'As present processes are thought to explain all past events , the Uniformitarianism slogan is " the present is the key to the past . "'
[EX A]: key

[EX Q]: Given Relationship: 'be capital city of', Sentence: 'London , the capital city of England and the United Kingdom today is one of the world 's leading business , financial and cultural centres .'
[EX A]: capital

[EX Q]: Given Relationship: 'be chairman of', Sentence: 'The President serves as chairman of the Board of Directors .'
[EX A]:
chairman