Is there any rule for determining whether a verb beginning with ε- will augment to η- vs ει-, or must all verbs' behaviors be memorized?

1. How do verbs work in Greek?
2. What is the Ancient Greek verb to know?
3. What are the contract verbs in ancient Greek?
4. What are the principal parts of ancient Greek verbs?

How do verbs work in Greek?

The Greek verb has two numbers, the singular and the plural, and three persons in each number as the English verb but unlike the English verb the person and the number in the Greek verb are included in the ending. Each person either in singular or in plural has a clearly distinguished ending.

What is the Ancient Greek verb to know?

The infinitive of οἶδα (oîda) is εἰδέναι (eidénai) "to know".

What are the contract verbs in ancient Greek?

There are three types of contract verbs: έω, άω, and όω.

What are the principal parts of ancient Greek verbs?

Verbs in Ancient Greek have six principal parts: present (I), future (II), aorist (III), perfect (IV), perfect middle (V) and aorist passive (VI), each listed in its first-person singular form: Part I forms the entire present system, as well as the imperfect.