Question: what kind of metric system does the us use
[{'answer': 'United States customary units', 'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 29, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'international units', 'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'start_paragraph_id': 3, 'start_character': 459, 'end_paragraph_id': 3, 'end_character': 478, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'answer': 'The International System of Units ( SI )'}, {'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'start_paragraph_id': 0, 'start_character': 0, 'end_paragraph_id': 0, 'end_character': 0, 'bleu_score': 1.0, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2642964473865761870}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 605, 'bleu_score': 0.679973860872085, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2642964473865761870}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 545, 'bleu_score': 0.976327165973018, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 2642964473865761870}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '39913055', 'title': 'Imperial and US customary measurement systems', 'section': 'Section::::Abstract.', 'start_paragraph_id': 1, 'end_paragraph_id': 1, 'meta': {'evidence_span': ['the US customary system of measurement', 'The imperial system of measurement and the US customary system of measurement are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure.', 'The imperial system of measurement and the US customary system of measurement are both derived from an earlier English system of measurement which in turn can be traced back to Ancient Roman units of measurement, and Carolingian and Saxon units of measure']}}]}, {'provenance': [{'wikipedia_id': '32308', 'title': 'United States customary units', 'section': 'Section::::Abstract.', 'start_paragraph_id': 3, 'end_paragraph_id': 3, 'meta': {'evidence_span': ['Americans primarily use customary units in commercial activities, as well as for personal and social use. In science, medicine, many sectors of industry, and some of government and military, metric units are used. The International System of Units (SI), the modern form of the metric system, is preferred for many uses by the U.S. National Institute of Standards and Technology (NIST). For newer units of measure where there is no traditional customary unit, international units are used, sometimes mixed with customary units, such as electrical resistance of wire expressed in ohms (SI) per thousand feet.', 'Americans primarily use customary units in commercial activities, as well as for personal and social use. In science, medicine, many sectors of industry, and some of government and military, metric units are used. The International System of Units (SI), the modern form of the metric system, is preferred for many uses by the U.S. National Institute of Standards and Technology (NIST). For newer units of measure where there is no traditional customary unit, international units are used, sometimes mixed with customary units, such as electrical resistance of wire expressed in ohms (SI) per thousand feet.']}}]}]