The stem of the first aorist passive is formed by adding -θη- (or -θε-) directly to the verb-stem: ἐ-λύ-θη-ν
a. -θη- appears in the indicative, imperative (except the third plural), and infinitive; -θε- appears in the other moods. -θη- is found before a single consonant, -θε- before two consonants or a vowel except in the nom. neuter of the participle.585aD
For -θησαν we find -θεν in Hom., as διέκριθεν.586
The verb-stem agrees with that of the perfect middle herein:
a. Vowel verbs lengthen the final vowel of the verb-stem, as τε-τί_μη-μαι, ἐ-τι_μή-θην. On verbs which do not lengthen their final vowel, see cross488.
b. Liquid stems of one syllable change ε to α, as τέ-τα-μαι, ἐ-τά-θην (τείνω
ἐστράφθην is Ionic and Doric; Hom. and Hdt. have ἐτράφθην from τρέπω. Hom. has ἐτάρφθην and ἐτέρφθην from τέρπω
c. Primitive verbs showing in their stems the gradations ε (ει, ευ): ο (οι, ου): α (ι, υ) have a strong form, as ἐτρέφθην from τρέπω (τρεπ-, τροπ-, τραπ-)
d. Primitive verbs showing in their stems a variation between ε: η and ο: ω have, in the first aorist passive, the short vowel. Thus, τίθημι (θε-, θη-) ἐτέθην, δίδωμι (δο-, δω-) ἐδόθην.
e. Final ν is dropped in some verbs: κέ-κρι-μαι, ἐκρίθην. See cross491.586eD
Hom. has ἐκλίνθην and ἐκλίθην, ἐκρίνθην and ἐκρίθην; ἱδρύνθην = Att. ἱδρύ_θην (ἱδρύω
f. The verb-stem may suffer metathesis: βέ-βλη-μαι, ἐ-βλή-θην. See cross492.
g. Sigma is often added: κε-κέλευς-μαι, ἐ-κελεύς-θην. See cross489.587
λείπ-ω ἐλείφ-θην, βλάπτω (βλαβ-) ἐβλάφ-θην; φυλάττω (φυλακ-) ἐφυλάχ-θην, ἄγ-ω ἤχ-θην; κομίζω (κομιδ-) ἐκομίς-θην, πείθ-ω ἐπείς-θην; γράφ-ω ἐγράφ-θην, ταράττω (ταραχ-) ἐταράχ-θην.
θ of the verb-stem becomes τ in ἐ-τέ-θην, and in ἐ-τύ-θην for ἐ-θυ-θην from τίθημι (θε-, θη-)
The stem of the first future passive is formed by adding -σόε- to the stem of the first aorist passive. It ends in -θησομαι. Thus, παιδευθή-σομαι
τι_μάω, ἐτι_μήθην τι_μηθήσομαι; ἐάω, εἰά_θην ἐα_θήσομαι; λείπω, ἐλείφθην λειφθήσομαι; πείθω, ἐπείσθην πεισθήσομαι; τείνω, ἐτάθην ταθήσομαι; τάττω, ἐτάχθην ταχθήσομαι; τίθημι, ἐτέθην τεθήσομαι; δίδωμι, ἐδόθην δοθήσομαι; δείκνυ_μι, ἐδείχθην δειχθήσομαι.589D
Hom. has no example of the first future passive. To express the idea of the passive future the future middle is used. See cross802. Doric shows the active endings in both futures passive: δειχθησοῦντι, ἀναγραφησεῖ.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].