Question: when did ronaldo started playing for manchester united
[{'answer': '2003', 'provenance': [{'wikipedia_id': '623737', 'title': 'Cristiano Ronaldo', 'start_paragraph_id': 2, 'start_character': 265, 'end_paragraph_id': 2, 'end_character': 269, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]