Question: when was the last time lake ontario frozen over
[{'answer': 'February 1934', 'provenance': [{'wikipedia_id': '17947', 'title': 'Lake Ontario', 'start_paragraph_id': 28, 'start_character': 395, 'end_paragraph_id': 28, 'end_character': 408, 'bleu_score': 1.0, 'section': 'Section::::Climate.\n'}]}]