[In traditional grammars durative is named "present", durative past indicative "imperfect"]

5. [Reduplication – (ι)σκ-] Here we encounter similar problems to 2. above. Full enumeration of these verbs, with other stems, all of which may be found in the list of verb stems:

βιβρώσκω, βρο-, βρου-

γιγνώσκω, γνο-, γνου-

διδράσκω

κικλήσκω, καλ-, καλε-

μιμνήσκω, /-ῃσκω, μνε-, μνησ-πιπίσκω, πι(σ)-            

πιπράσκω, πιπρήσκω

πιφαύσκω

τιτύσκω, τυκ-

τιτρώσκω

 διδράσκω in Attic almost only with  ἀπο-