Question: who is the actor that plays ducky on ncis
[{'answer': 'David McCallum', 'provenance': [{'wikipedia_id': '328383', 'title': 'David McCallum', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '328383', 'title': 'David McCallum', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 190, 'bleu_score': 0.929712191543383, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18036154638215976688}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '328383', 'title': 'David McCallum', 'section': 'Section::::Abstract.', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 190, 'bleu_score': 1.0}]}]