Question: when did romania become part of the eu
[{'answer': '1 January 2007', 'provenance': [{'wikipedia_id': '24299732', 'title': '2007 enlargement of the European Union', 'start_paragraph_id': 1, 'start_character': 100, 'end_paragraph_id': 1, 'end_character': 114, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '24299732', 'title': '2007 enlargement of the European Union', 'start_paragraph_id': 10, 'start_character': 0, 'end_paragraph_id': 10, 'end_character': 238, 'bleu_score': 0.8723360571509821, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9560881117300759720}, 'section': 'Section::::Treaty.\n'}]}]