FormPersonMorphological clue
وَقَى3m singularfinal yāʾ changes to alif
وَقَيَا3m dualyāʾ before the dual suffix
وَقَوْا3m pluralplural wāw appears at the end
وَقَتْ3f singularfinal weak consonant deleted
وَقَيْتُ1st singularroot yāʾ appears before -tu
The plural-marker wāw is not the root-initial wāw. In وَقَوْا the word begins with the first radical and ends with a plural suffix. وَقَتْ has lost its final yāʾ on the surface, without changing the underlying root.