Question: when does an embryo attach to the uterus
[{'answer': 'about 9 days after ovulation', 'provenance': [{'wikipedia_id': '7357937', 'title': 'Implantation (human embryo)', 'start_paragraph_id': 4, 'start_character': 311, 'end_paragraph_id': 4, 'end_character': 339, 'bleu_score': 0.668740304976422, 'section': 'Section::::Implantation window.\n'}]}, {'provenance': [{'wikipedia_id': '7357937', 'title': 'Implantation (human embryo)', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 150, 'bleu_score': 0.5421505875750391, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 4042227166727257183}, 'section': 'Section::::Abstract.'}]}]