past open
If you did X, you were Y
εἰ + any past ind.
+
any past ind.
present open
If you do X, you are Y
εἰ + present ind.
+
present ind.
future open
If X happens, Y will happen
ἐαν + subjunctive OR εἰ + future ind. \+ future ind.
past unfulfilled
If X HAD happenED, Y WOULD HAVE
εἰ + aorist ind.
+
ἀν + aorist ind.
present unfulfilled
If they were doing X, they would be Y
εἰ + imperfect ind.
+
ἀν + imperfect ind.
future remote
If X were to happen, Y would
εἰ + optative
+
ἂν + optative
negative in protasis
μη
negative in apodosis
ου
whether… or…
είτε… είτε…