Dear Board,
The perfect middle 3rd plural often has a periphrastic construction with the perfect middle participle plus appropriate forms of εἰμί. While I was at school I never thought to dig deeper into this topic, but now it’s come back to me that it is quite remarkable this is the only periphrastic form taught as a rule in an introductory course.
It seemed especially strange to me since I started reading about the evolution from the proto-language, where a synthetic form should not be impossible. Consider for example the athematic present 3rd plural ending -ασι(ν) < *-ντι. If the original forms were primary *-νται secondary *-ντο, should these not very easily result in primary *-αται and secondary *-ατο, following a consonant stem?
Could anyone kindly shed some light on this form?