Question: when did alaska become part of the usa
[{'answer': 'March 30 , 1867', 'provenance': [{'wikipedia_id': '624', 'title': 'Alaska', 'start_paragraph_id': 49, 'start_character': 3, 'end_paragraph_id': 49, 'end_character': 18, 'bleu_score': 1.0, 'section': 'Section::::History.:Colonization.\n'}]}, {'provenance': [{'wikipedia_id': '624', 'title': 'Alaska', 'start_paragraph_id': 2, 'start_character': 33, 'end_paragraph_id': 2, 'end_character': 365, 'bleu_score': 0.965203995518735, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7136251835278484169}, 'section': 'Section::::Abstract.'}]}]