λύω

Six principal parts of λύω:

1. λύω — present + imperfect systems
2. λύσω — future active/middle
3. ἔλυσα — aorist active/middle
4. λέλυκα — perfect/pluperfect active
5. λέλυμαι — perfect/pluperfect middle-passive
6. ἐλύθην — aorist/future passive

Stem-building signals:

• augment ἐ- — past indicative only — ἔλυον, ἔλυσα, ἐλύθην
• future -σ- — future active/middle — λύσω
• aorist -σα- — 1st aorist active/middle — ἔλυσα
• reduplication — perfect system — λέλυκα, λέλυμαι
• perfect active -κ- — perfect active marker — λέλυκα
• passive -θη- — aorist passive stem — ἐλύθην

Five things to parse in every finite verb:

1. Person — 2. Number — 3. Tense — 4. Mood — 5. Voice

Important: outside the indicative, “tense” usually expresses aspect more than absolute time. Your grammar textbook will teach this distinction in syntax.