Question: when did vietnam free itself from chinese control
[{'answer': '938 AD', 'provenance': [{'wikipedia_id': '38163162', 'title': 'Chinese domination of Vietnam', 'start_paragraph_id': 1, 'start_character': 125, 'end_paragraph_id': 1, 'end_character': 131, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '38163162', 'title': 'Chinese domination of Vietnam', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 458, 'bleu_score': 0.828829173685186, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10746004753706865716}, 'section': 'Section::::Abstract.'}]}]