Question: who is presiding officer of the us senate
[{'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.'}]}, {'answer': 'an elected United States Senator', 'provenance': [{'wikipedia_id': '5626102', 'title': 'Presiding Officer of the United States Senate', 'start_paragraph_id': 1, 'start_character': 394, 'end_paragraph_id': 1, 'end_character': 426, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'in special cases , the Chief Justice'}, {'provenance': [{'wikipedia_id': '5626102', 'title': 'Presiding Officer of the United States Senate', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 645, 'bleu_score': 0.9813933169956551, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4788039901168633843}, 'section': 'Section::::Abstract.'}]}]