Following the stem of the vowel is a κ which is then followed by the specific ending. Hence, a perfect active verb can be recognized by the presence of reduplication and a κ.
For [[Koine Greek: Contract Verbs - Contract|contract verbs]] (εω, αω and οω verbs) the final vowel undergoes a lengthening prior to the κ+ending being added - α becomes η, ε becomes η and ο becomes ω
Verbs ending with '''τ''' or '''θ''' or '''δ''' or '''ζ''' drop the last letter before adding the κ