Question: when were planes first used in world war 1
[{'answer': '1914', 'provenance': [{'wikipedia_id': '768600', 'title': 'Aviation in World War I', 'start_paragraph_id': 7, 'start_character': 181, 'end_paragraph_id': 7, 'end_character': 185, 'bleu_score': 1.0, 'section': 'Section::::The early years of war.\n'}]}, {'provenance': [{'wikipedia_id': '768600', 'title': 'Aviation in World War I', 'start_paragraph_id': 7, 'start_character': 0, 'end_paragraph_id': 7, 'end_character': 652, 'bleu_score': 0.980097014099621, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 957459063567415072}, 'section': 'Section::::The early years of war.\n'}]}]