Question: when did poland become part of the eu
[{'answer': '1 May 2004', 'provenance': [{'wikipedia_id': '21133193', 'title': '2004 enlargement of the European Union', 'start_paragraph_id': 1, 'start_character': 252, 'end_paragraph_id': 1, 'end_character': 262, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21133193', 'title': '2004 enlargement of the European Union', 'start_paragraph_id': 53, 'start_character': 0, 'end_paragraph_id': 53, 'end_character': 558, 'bleu_score': 0.9370565785335291, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 8340498037953934618}, 'section': 'Section::::New member states.:Poland.\n'}]}]