The ultima, if long and accented, may have a circumflex (whether in isolation or not) or an acute (in isolation or before punctuation or enclitic; otherwise a grave is substituted). In this case the type of accent must be learned for each word or particular inflectional pattern.
ἡ ὁδὸς μακρά. “The road is long.”
μακρὰ ἡ ὁδός. “The road is long.”
τὸν ποιητὴν διαβάλλει. “He slanders the poet.”
τοῦ ποιητοῦ κατηγορεῖ. “He accuses the poet.”
κατηγορεῖ τοῦ ποιητοῦ. “He accuses the poet.”