Question: when did the second battle of ypres start
[{'answer': '22 April', 'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 14, 'start_character': 3, 'end_paragraph_id': 14, 'end_character': 11, 'bleu_score': 1.0, 'section': 'Section::::Battle.:Battle of Gravenstafel Ridge (22–23 April 1915).\n'}]}, {'answer': '1915', 'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 7, 'start_character': 475, 'end_paragraph_id': 7, 'end_character': 479, 'bleu_score': 1.0, 'section': 'Section::::Battle.\n'}]}, {'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 491, 'bleu_score': 0.664989437940767, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3528300233383489840}, 'section': 'Section::::Abstract.'}]}]