Question: who has been chief of surgery on grey's
[{'answer': 'Richard Webber', 'provenance': [{'wikipedia_id': '7687030', 'title': 'Richard Webber', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'Owen Hunt', 'provenance': [{'wikipedia_id': '7687030', 'title': 'Richard Webber', 'start_paragraph_id': 1, 'start_character': 375, 'end_paragraph_id': 1, 'end_character': 384, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '7687030', 'title': 'Richard Webber', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 316, 'bleu_score': 0.8803173774565051, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3045507575893838839}, 'section': 'Section::::Abstract.'}]}]