How to form the aorist passive (and future passive):

 

1) First form the base, from present stem stripping away present markers (the same sort of ‘infices’ lost in 2nd aorist actives, ¨

          like -λαβ-ον  from λα-μ-β-αν-ω, losing the present infices, μ-αν

 

2) Add that base to the passive marker –θη-,

 

    a) Stops to go their corresponding aspirate or –s-;

        stops (voiced  or voiceless)  --->        aspirate  or –s-                before θ

labial

 β  or π  --->

φ

velar (back)

γ  or  κ  ---->

χ

dental

δ/ζ  or τ  ----->

σ

 

and often the vowel lengthens, λαβ --> -λήφ-θη-ν

 

    b) vowel-stems lengthen (as in aor.act.): φιλέ-ω --> ἐ-φιλή-θη-ν

 

3) Then add past endings for aorist --- -ν, -ς, --  ,  -μεν, -τε, -σαν

 

For future (of course, no augment) add  -σο- plus middle endings:

 -σο-μαι, -σει, -σεται, -σομεθα, κτλ.

 

4) Give up figuring it out and just learn principle parts.