Tuftaḥu an-nawāfidhu: feminine singular passive imperfect can be used with the nonhuman broken plural an-nawāfidhu, which is nominative passive subject. The verb is not plural simply because the noun is plural.
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Case 7: Nonhuman Plural Agreement
Advanced Parsing Workshop: Integrated Grammar
Tuftaḥu an-nawāfidhu: feminine singular passive imperfect can be used with the nonhuman broken plural an-nawāfidhu, which is nominative passive subject. The verb is not plural simply because the noun is plural.