Omission of the Apodosis.—a. When the conclusion is it is well (καλῶς ἔχει) or the like, it is often omitted. So often when the second of alternative opposing suppositions is expressed by εἰ δὲ μή ( cross2346 d, N. 3). Cp. “yet now, if thou wilt forgive this sin, —: and if not, blot me . . . out of thy book” (Exodus 32. cross32).
b. When we should introduce the conclusion by know that or I tell you: εἰ καὶ οἴει με ἀδικοῦντά τι ἄγεσθαι, οὔτε ἔπαιον οὐδένα οὔτε ἔβαλλον
c. Sometimes when the protasis is merely parenthetical:
ὁ χρυ_σός, εἰ βούλοιο τἀ_ληθῆ λέγειν, ἔκτεινε τὸν ἐμὸν παῖδα
d. In passionate speech for rhetorical effect (aposiopēsis, cross3015): εἴ περ γάρ κ' ἐθέλῃσιν Ὀλύμπιος ἀστεροπητὴς ἐξ ἑδέων στυφελίξαι· ὁ γὰρ πολὺ φέρτατός ἐστιν
e. There is properly no omission of an apodosis after clauses with εἰ, εἰ γάρ, εἴθε, etc., in wishes (see cross1816). In such clauses it is often possible to find an apodosis in an appended final clause:
ποτανὰ_ν εἴ μέ τις θεῶν κτίσαι, διπόταμον ἵνα πόλιν μόλω
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].