Question: when did lithuania become part of the soviet union
[{'answer': '1940', 'provenance': [{'wikipedia_id': '404449', 'title': 'Lithuanian Soviet Socialist Republic', 'start_paragraph_id': 1, 'start_character': 221, 'end_paragraph_id': 1, 'end_character': 225, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]