Question: what force did the romans use to move water
[{'answer': 'gravity', 'provenance': [{'wikipedia_id': '3745201', 'title': 'Roman aqueduct', 'start_paragraph_id': 2, 'start_character': 30, 'end_paragraph_id': 2, 'end_character': 37, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '3745201', 'title': 'Roman aqueduct', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 781, 'bleu_score': 0.9828310228624961, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3096737378252357842}, 'section': 'Section::::Abstract.'}]}]