Question: when did the korean war became a stalemate
[{'answer': 'began 10 July 1951'}, {'provenance': [{'wikipedia_id': '16772', 'title': 'Korean War', 'start_paragraph_id': 105, 'start_character': 52, 'end_paragraph_id': 105, 'end_character': 729, 'bleu_score': 0.7847504534626151, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15916296519193108621}, 'section': 'Section::::Course of the war.:Stalemate (July 1951 – July 1953).\n'}]}]