Question: when did the classical period of ancient greece begin
[{'answer': '510 BC', 'provenance': [{'wikipedia_id': '11936957', 'title': 'Classical Greece', 'start_paragraph_id': 1, 'start_character': 720, 'end_paragraph_id': 1, 'end_character': 726, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '11936957', 'title': 'Classical Greece', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 908, 'bleu_score': 0.962665811710344, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 11542683721946066756}, 'section': 'Section::::Abstract.'}]}]