Question: how long does it take wood to petrified
[{'answer': 'millions of years'}, {'provenance': [{'wikipedia_id': '431109', 'title': 'Petrified wood', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 570, 'bleu_score': 0.892368842713367, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 5370935829553183680}, 'section': 'Section::::Abstract.'}]}]