Breakdown of Það er bannað að reykja inni.
vera
to be
það
it / there (existential) / the one (n)
inni
inside
að
to (infinitive marker)
Questions & Answers about Það er bannað að reykja inni.
This lesson is about the modal verb mega. How would I say this same rule using mega?
You could say Það má ekki reykja inni (One may not smoke inside). Notice that if you use má, you drop the word að and just use the bare infinitive reykja. This sentence uses the adjective bannað (forbidden) instead, which requires the full infinitive að reykja.
Why is there an að before reykja in this sentence?
Because bannað is an adjective, not a modal verb. When you say it is forbidden 'to smoke', you use the standard infinitive form with að. Modal verbs like mega (may) or skulu (shall) are special because they take the bare infinitive, meaning you drop the að.
Why is the word for inside inni rather than inn?
Icelandic has different words for direction (moving towards a place) and position (being in a place). Inni is the stationary form, used because the action of smoking is happening in a fixed location inside. If you were moving into the building from the outside, you would use the movement form inn.
Why does the word bannað end in -ð?
It is the neuter singular form of the adjective bannaður (forbidden). It takes this neuter form to match the dummy subject pronoun Það (It) at the very start of the sentence.