Present-Unreal Conditionals (αν + imperfect, θα + imperfect)
An UNREAL (hypothetical) conditional about NOW imagines something contrary to fact: “If I had time (but I don’t), I would read.” Greek marks BOTH clauses with the IMPERFECT: αν + imperfect in the condition, θα + imperfect in the result - Αν είχα χρόνο, θα διάβαζα. This is the key contrast with the REAL conditional (αν + present, θα + future = Αν έχω χρόνο, θα διαβάσω, a live possibility): the unreal one swaps both verbs into the imperfect to signal “this isn’t actually so”. The condition uses the IMPERFECT, never the aorist - it is the imperfective, unreal past that carries the hypothetical sense.
The rule
The present-unreal conditional is contrary to fact now: “If I had time (but I don’t), I would read.” Greek puts both verbs in the imperfect - αν + imperfect in the condition, θα + imperfect in the result: Αν είχα χρόνο, θα διάβαζα, Αν ήμουν πλούσιος, θα ταξίδευα. Contrast the real conditional Αν έχω χρόνο, θα διαβάσω (αν + present, θα + future = a live possibility): the unreal one swaps both verbs into the imperfect to signal “this isn’t actually so”. The θα still marks the result clause; the condition uses the imperfect, never the aorist.