The verb you use for sentences like "I was a librarian" "The ball is red" or "We are here" is called copula and not all languages use verb to express it - and Dothraki does not. Existential claims like "Librarians exits" are a bit different, and for them Dothraki has at least a verb
vekhat.
Many sentences that in English are copula sentences are actually not in Dothraki, because Dothraki has a lot of stative verbs that can be used for assigning qualities. All adjectives have verb forms. Think how you can use a verb
to stand or and adjective like
erect or
upright. Well, Dothraki can do this with any real adjective, so they don't need to say stuff like "The ball is red" or "The man was tall." They saometimes still say, but rarely. Mostly they just say ~ "The ball reds" and "The man talled".
When Dothraki want to use a true copula sentence, they use zero-copula (see
http://wiki.dothraki.org/Syntax#Zero_Copula_Sentences and
http://www.dothraki.com/2011/12/to-be-or-not-to-be/). This is, funnily, akin to the way English imitate primitive speak: "Me Tarzan, you Jane".
Yer villi - "you are wise"
Yer ville - "you are wise" using zero-copula to stress that this is a general quality you have, not a momentarily state.
