Question: where was the first world's fair held
[{'answer': '1851', 'provenance': [{'wikipedia_id': '50268', 'title': "World's fair", 'start_paragraph_id': 10, 'start_character': 106, 'end_paragraph_id': 10, 'end_character': 110, 'bleu_score': 1.0, 'section': 'Section::::History.\n'}]}, {'provenance': [{'wikipedia_id': '50268', 'title': "World's fair", 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 673, 'bleu_score': 0.674941143619863, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17422960803218422160}, 'section': 'Section::::History.\n'}]}]