Thread: Past passive participle

here's another one

застегнуть - застёгивать - застёгнутый


i think i figured a tentative rule for these verbs, not sure if it's any philological revelation though

this pattern applies to verbs with -нуть ending in perfect infinitive form where -н- is not the part of the stem
it's rather not clear cut (like in the case of согнуть) but generally it's true

sometimes instead of -ё- the participle receives -о- which is a similar sound, only in this case you can't rely on the verb's imperfect infinitive form for guidance

взболтнуть - взбалтывать - взболтанный (not взболтнутый however)
проткнуть - протыкать - проткнутый (not a literary word, but grammatically correct)

suffix -нуть signifies a momentary action and many verbs can receive it