Conditional sentences may be classified according to form or function (i.e. with reference to their meaning). Classified according to form, all conditional sentences may be arranged with regard to the form of the protasis or of the apodosis.
Protasis: εἰ with the indicative.
ἐά_ν (rarely εἰ) with the subjunctive.
εἰ with the optative.
Apodosis: with ἄν, denoting what would (
without ἄν, not denoting what would (
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].