Question: what kind of wood is a stradivarius violin made of
[{'answer': 'spruce for the top', 'provenance': [{'wikipedia_id': '153773', 'title': 'Stradivarius', 'start_paragraph_id': 4, 'start_character': 24, 'end_paragraph_id': 4, 'end_character': 42, 'bleu_score': 1.0, 'section': 'Section::::Construction.\n'}]}, {'answer': 'willow for the internal blocks and linings'}, {'answer': 'maple for the back , ribs , and neck'}, {'provenance': [{'wikipedia_id': '153773', 'title': 'Stradivarius', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 254, 'bleu_score': 0.618174973868839, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 53961620800262294}, 'section': 'Section::::Construction.\n'}]}]