Question: when is the tomb of the unknown soldier guarded
[{'answer': 'continuously', 'provenance': [{'wikipedia_id': '67991', 'title': 'Tomb of the Unknown Soldier (Arlington)', 'start_paragraph_id': 55, 'start_character': 330, 'end_paragraph_id': 55, 'end_character': 342, 'bleu_score': 1.0, 'section': 'Section::::Tomb guards.:Dedication.\n'}]}, {'provenance': [{'wikipedia_id': '67991', 'title': 'Tomb of the Unknown Soldier (Arlington)', 'start_paragraph_id': 55, 'start_character': 0, 'end_paragraph_id': 55, 'end_character': 472, 'bleu_score': 0.9361374222844411, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 18366192789937129469}, 'section': 'Section::::Tomb guards.:Dedication.\n'}]}]