"He is going past our house to the restaurant."
Translation:Li iras preter nia domo al la restoracio.
Should it not be "al la restoracion" because it is a destination?
Yes, if you want to emphasise that he did not stop there and continued further. Here is a helpful link that I saw in another thread discussing this question: http://bertilow.com/pmeg/gramatiko/rolmontriloj/rolvortetoj/lokaj_rolvortetoj/preter.html#i-arh
preter by, straight past, beyond, past
Li iras preter nia domo al la restoracio.
He is going past our house to the restaurant.
On his way to the restaurant, he goes past our house.
On his way to the restaurant, he is passing our house.
(Maybe our house is on the same road as the restaurant?)
post after, behind
Li iras post nia domo al la restoracio.
He is going after our house to the restaurant.
(Our house is going to the restaurant, and so is he, so he tags along ... ?)
(Our house seems to be able to move on its own ...
Because -n is used with prepositions that can indicate both place and direction. Al can only mean direction (and not movement in some place), so there's no ambiguity.
I used iras and it said I was wrong for not using iranta? Even when I click on the translation for "going" the pop up says iras.
Well, in this example he is walking to the restaurant (from wherever he is), not into it (from outside of it)
en la restoracion - into the restaurant
ĝis la restoracio - to the restaurant, as far as the restaurant
I think "n" is an ending which adds meaning of destination to prepositions which they initially don't have, so neither "al la restoracion" (because "al" is already a destination preposition) nor "preter domon" (because there is no destination "to somewhere past something" in the sentence) are good here.