Question: what is the main airport in washington dc
[{'answer': 'Baltimore - Washington International Airport'}, {'provenance': [{'wikipedia_id': '33591', 'title': 'Washington Dulles International Airport', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 703, 'bleu_score': 0.7347622956796651, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17045953395792288646}, 'section': 'Section::::Abstract.'}]}]