Question: who was the first lead singer for ac dc
[{'answer': 'Dave Evans', 'provenance': [{'wikipedia_id': '149225', 'title': 'AC/DC', 'start_paragraph_id': 11, 'start_character': 95, 'end_paragraph_id': 11, 'end_character': 105, 'bleu_score': 1.0, 'section': 'Section::::History.:Early years.\n'}]}]