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2009年4月22日是世界地球日,美国总统奥巴马在这一天倡导新能源利用,并前往爱荷华州宣传其能源计划,奥巴马敦促美国在发展可再生能源方面
On April 22, 2009, Earth Day, US President Barack Obama advocated the use of new energy on this day and traveled to Iowa to promote its energy program. Obama urged the United States to promote the development of renewable energy