Which radicals underlie iʿtaḍada?Six Semantic Functions of Form VIII (Iftiʿāl): Adoption, Exertion, Selection, Response, Equivalence, and Independent Usagealif–ʿayn–tāʾḍād–dāl–tāʾʿayn–tāʾ–ḍādʿayn–ḍād–dāl