Question: when did the us start building the panama canal
[{'answer': 'January 1 , 1881', 'provenance': [{'wikipedia_id': '2869783', 'title': 'History of the Panama Canal', 'start_paragraph_id': 22, 'start_character': 35, 'end_paragraph_id': 22, 'end_character': 51, 'bleu_score': 1.0, 'section': 'Section::::French project.:Construction.\n'}]}, {'provenance': [{'wikipedia_id': '2869783', 'title': 'History of the Panama Canal', 'start_paragraph_id': 22, 'start_character': 0, 'end_paragraph_id': 22, 'end_character': 457, 'bleu_score': 0.974188104609039, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8532792202467747908}, 'section': 'Section::::French project.:Construction.\n'}]}]