Question: when did moldova become part of the ussr
[{'answer': '2 August 1940', 'provenance': [{'wikipedia_id': '376728', 'title': 'Moldavian Soviet Socialist Republic', 'start_paragraph_id': 1, 'start_character': 153, 'end_paragraph_id': 1, 'end_character': 166, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]