Question: when did the us join world war one
[{'answer': 'April 6 , 1917', 'provenance': [{'wikipedia_id': '25162935', 'title': 'American entry into World War I', 'start_paragraph_id': 100, 'start_character': 3, 'end_paragraph_id': 100, 'end_character': 17, 'bleu_score': 1.0, 'section': 'Section::::Declaration of war.:Germany.\n'}]}]