Question: who won the academy award for best actor in 1939
[{'answer': 'Robert Donat', 'provenance': [{'wikipedia_id': '4727465', 'title': '12th Academy Awards', 'start_paragraph_id': 39, 'start_character': 0, 'end_paragraph_id': 39, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Ceremony.\n'}]}]