Question: what is the term for materials that do not transmit light
[{'answer': 'opaque', 'provenance': [{'wikipedia_id': '351077', 'title': 'Transparency and translucency', 'start_paragraph_id': 4, 'start_character': 49, 'end_paragraph_id': 4, 'end_character': 55, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '351077', 'title': 'Transparency and translucency', 'start_paragraph_id': 4, 'start_character': 0, 'end_paragraph_id': 4, 'end_character': 598, 'bleu_score': 0.978138775770484, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 7011636592845880652}, 'section': 'Section::::Abstract.'}]}]