Question: when did the construction of the eiffel tower start and end
[{'answer': '28 January 1887', 'provenance': [{'wikipedia_id': '9232', 'title': 'Eiffel Tower', 'start_paragraph_id': 18, 'start_character': 35, 'end_paragraph_id': 18, 'end_character': 50, 'bleu_score': 1.0, 'section': 'Section::::History.:Construction.\n'}]}, {'provenance': [{'wikipedia_id': '9232', 'title': 'Eiffel Tower', 'start_paragraph_id': 18, 'start_character': 0, 'end_paragraph_id': 18, 'end_character': 561, 'bleu_score': 0.753379703328481, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11615443903356344331}, 'section': 'Section::::History.:Construction.\n'}]}]