Question: why is the us canada's largest trading partner
[{'answer': 'Free Trade Agreement', 'provenance': [{'wikipedia_id': '29368556', 'title': 'List of the largest trading partners of Canada', 'start_paragraph_id': 2, 'start_character': 1038, 'end_paragraph_id': 2, 'end_character': 1058, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '29368556', 'title': 'List of the largest trading partners of Canada', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 1402, 'bleu_score': 0.9912851953131591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 16066779675462095740}, 'section': 'Section::::Abstract.'}]}]