Question: in the senate the blank is the official chair of the chamber
[{'answer': 'Vice President', 'provenance': [{'wikipedia_id': '5626102', 'title': 'Presiding Officer of the United States Senate', 'start_paragraph_id': 1, 'start_character': 378, 'end_paragraph_id': 1, 'end_character': 392, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '5626102', 'title': 'Presiding Officer of the United States Senate', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 745, 'bleu_score': 0.984188478234951, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 6725194002875864812}, 'section': 'Section::::Abstract.'}]}]