Question: who participated in the second battle of ypres
[{'answer': 'Germany', 'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 1, 'start_character': 250, 'end_paragraph_id': 1, 'end_character': 257, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1st Canadian Division', 'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 1, 'start_character': 353, 'end_paragraph_id': 1, 'end_character': 374, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'German Empire', 'provenance': [{'wikipedia_id': '560821', 'title': 'Second Battle of Ypres', 'start_paragraph_id': 1, 'start_character': 407, 'end_paragraph_id': 1, 'end_character': 420, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'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': 17643561424360130479}, 'section': 'Section::::Abstract.'}]}]