The preposition "post" takes an accusative object, and thus "primam horam."
that's why i came here thanks!
Understood, but left me wondering why 'hora' was the first option on the hover list?
The vocabulary is glossed in the nominative form. Latin adds endings to nouns (among other words), thus changing their form in context.
Why didn't it accept : post tertia hora primam horam est ?
The preposition “post” takes the accusative and needs to come right before it’s object (“primam horam”).
You can move other words in a sentence around, but prepositional phrases must stay together.
Oups, I get my wired completely crossed, I though that "post" could be after like "primam horam post", but that's not true, as it's a preposition, it always come first.
"Post" can also be used adverbially ("later"), in which case it won't be governing an accusative (as it does when used as a preposition).
Why is there a problem with word order "est" in middle or at end
The verb usually comes at the end but its position can vary.