Die Frage, wie praxisrelevant eine Verknüpfung des present perfect continuous mit einem Modalverb ist, lassen wir dahingestellt, es ist zumindest eine theoretische Möglichkeit, die in der Praxis auch tatsächlich auftritt. Wer zweifelt, der möge einfach googeln und sich davon überzeugen. Die Bildung betreffend bleibt die Logik dieselbe (siehe auch Kapitel 8.3.5 ).

Beispiel
present perfect des Modalverbs + Vollverb + Endung -ing = Verlaufsform
he might have been do ing he might have been doing
she could have been writ(e) ing she could have been writing
we have to have been jump ing we have to have been jumping
they should have been sell ing they should have been selling
you need to have been study ing you need to have been studying
I ought to have been watch ing I ought to have been watching