Question: when were air brakes first used on trucks
[{'answer': 'the early 20th century', 'provenance': [{'wikipedia_id': '6889398', 'title': 'Air brake (road vehicle)', 'start_paragraph_id': 1, 'start_character': 716, 'end_paragraph_id': 1, 'end_character': 738, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '6889398', 'title': 'Air brake (road vehicle)', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 854, 'bleu_score': 0.9685451587663261, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14908331553118801835}, 'section': 'Section::::Abstract.'}]}]