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.

Q: Given Relationship: 'be professor of', Sentence: 'Your nerves learn to communicate more effectively with your muscle cells , allowing the muscle to recruit more cells during each contraction , says Mark A. W. Andrews , PhD , associate professor of physiology at Lake Erie College of Osteopathic Medicine in Erie , Pa .'

A: professor
****
Q: Given Relationship: 'be president of', Sentence: 'Tomorrow Barack Obama will become president of the United States .'

A: president
****
Q: Given Relationship: 'declare war on', Sentence: 'When the United States declared war on Germany on April 6 , 1917 , Hemingway tried to enlist in the army .'

A:
declared
****