Question: when did the united states officially entered ww2
[{'answer': '8 December 1941'}, {'provenance': [{'wikipedia_id': '4653534', 'title': 'Military history of the United States during World War II', 'start_paragraph_id': 110, 'start_character': 0, 'end_paragraph_id': 110, 'end_character': 571, 'bleu_score': 0.8925531896020411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17338475047113734293}, 'section': 'Section::::Pacific Theater.:The Attack on Pearl Harbor.\n'}]}]