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NEW YORK - SEPTEMBER 11: U.S. Vice President Joe Biden looks up at One World Trade Center as he arrives at Ground Zero for the annual memorial service September 11, 2010 in New York City. Thousands will gather to pay a solemn homage on the ninth anniversary of the terrorist attacks that killed nearly 3,000 people on September 11, 2001. (Photo by Lucas Jackson-Pool/Getty Images)

NEW YORK - SEPTEMBER 11:  U.S. Vice President Joe Biden looks up at One World Trade Center as he arrives at Ground Zero for the annual memorial service September 11, 2010 in New York City. Thousands will gather to pay a solemn homage on the ninth anniversary of the terrorist attacks that killed nearly 3,000 people on September 11, 2001.   (Photo by Lucas Jackson-Pool/Getty Images)