Question: who won the 2017 china open tennis tournament
[{'answer': 'Rafael Nadal', 'provenance': [{'wikipedia_id': '55366821', 'title': "2017 China Open – Men's Singles", 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '55366821', 'title': "2017 China Open – Men's Singles", 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 63, 'bleu_score': 0.610216920255791, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7949093646211552121}, 'section': 'Section::::Abstract.'}]}]