Question: when did construction start on the sydney harbour bridge
[{'answer': 'on 28 July 1923', 'provenance': [{'wikipedia_id': '28267', 'title': 'Sydney Harbour Bridge', 'start_paragraph_id': 34, 'start_character': 70, 'end_paragraph_id': 34, 'end_character': 85, 'bleu_score': 1.0, 'section': 'Section::::History.:Construction.\n'}]}, {'provenance': [{'wikipedia_id': '28267', 'title': 'Sydney Harbour Bridge', 'start_paragraph_id': 34, 'start_character': 0, 'end_paragraph_id': 34, 'end_character': 210, 'bleu_score': 0.9493253852526031, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 326319713064915123}, 'section': 'Section::::History.:Construction.\n'}]}]