Question: what is the standard voltage in the us
[{'answer': '120 V', 'provenance': [{'wikipedia_id': '175959', 'title': 'Mains electricity', 'start_paragraph_id': 2, 'start_character': 297, 'end_paragraph_id': 2, 'end_character': 302, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '175959', 'title': 'Mains electricity', 'start_paragraph_id': 2, 'start_character': 0, 'end_paragraph_id': 2, 'end_character': 781, 'bleu_score': 0.9651324673660481, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 13497560389273301510}, 'section': 'Section::::Abstract.'}]}]