Question: when did world war 2 officially start and end
[{'answer': '1 September 1939', 'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 2, 'start_character': 183, 'end_paragraph_id': 2, 'end_character': 199, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '2 September 1945', 'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 9, 'start_character': 230, 'end_paragraph_id': 9, 'end_character': 246, 'bleu_score': 1.0, 'section': 'Section::::Chronology.\n'}]}, {'answer': '1939', 'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 1, 'start_character': 119, 'end_paragraph_id': 1, 'end_character': 123, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1945', 'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 1, 'start_character': 127, 'end_paragraph_id': 1, 'end_character': 131, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': '1 September 1939 -- 2 September 1945'}, {'answer': 'September 1939 -- 2 September 1945 ('}, {'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12395453270640575864}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 670, 'bleu_score': 0.691519044551773, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 12395453270640575864}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32927', 'title': 'World War II', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['World War\xa0II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945.', "World War\xa0II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countriesincluding all the great powerseventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries. The major participants threw their entire economic, industrial, and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 70 to 85 million fatalities, most of whom were civilians in the Soviet Union and China. It included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, and the only use of nuclear weapons in war.", 'World War\xa0II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945.']}}]}]