Question: when was the last time man u beat arsenal
[{'answer': 'In August 2011', 'provenance': [{'wikipedia_id': '23909907', 'title': 'Arsenal F.C.–Manchester United F.C. rivalry', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 14, 'bleu_score': 1.0, 'section': 'Section::::History.:2005–present.\n'}]}, {'provenance': [{'wikipedia_id': '23909907', 'title': 'Arsenal F.C.–Manchester United F.C. rivalry', 'start_paragraph_id': 27, 'start_character': 0, 'end_paragraph_id': 27, 'end_character': 1019, 'bleu_score': 0.9132659676327991, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14653581028320149699}, 'section': 'Section::::History.:2005–present.\n'}]}]