Question: when was the boeing 747 first used for commercial service
[{'answer': '1970', 'provenance': [{'wikipedia_id': '4614', 'title': 'Boeing 747', 'start_paragraph_id': 1, 'start_character': 528, 'end_paragraph_id': 1, 'end_character': 532, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '4614', 'title': 'Boeing 747', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 589, 'bleu_score': 0.829727686935471, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10006819182496341688}, 'section': 'Section::::Abstract.'}]}]