Question: when did they finish building the transcontinental railroad
[{'answer': 'August 1870', 'provenance': [{'wikipedia_id': '36541', 'title': 'First Transcontinental Railroad', 'start_paragraph_id': 140, 'start_character': 490, 'end_paragraph_id': 140, 'end_character': 501, 'bleu_score': 1.0, 'section': 'Section::::Aftermath.:Railroad developments.\n'}]}, {'provenance': [{'wikipedia_id': '36541', 'title': 'First Transcontinental Railroad', 'start_paragraph_id': 140, 'start_character': 0, 'end_paragraph_id': 140, 'end_character': 679, 'bleu_score': 0.9405484323297301, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 620607780494977716}, 'section': 'Section::::Aftermath.:Railroad developments.\n'}]}]